Aircraft Cabin Air and Engine Oil – A Systems Engineering View

AIRCRAFT DESIGN AND SYSTEMS GROUP (AERO) Aircraft Cabin Air and Engine Oil  A Systems Engineering View Hamburg Aerospace Lecture Series (HALS) DGLR, RAeS, VDI, ZAL, HAW Hamburg together with VC and UFO Hamburg, 27th April, 2017 https://doi.org/10.5281/zenodo.1237858 Dieter Scholz Hamburg University of Applied Sciences (with backup slides and update) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 2 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Abstract Purpose – This presentation gives an introduction to aircraft cabin air quality and contamination risks. Beyond these fundamentals, most of the current engineering issues discussed with respect to the topic are explained. Design/methodology/approach – The literature review is complemented with own explanations, thoughts and derivations. Findings – There is a real health and flight safety risk due to contaminated cabin air. For the infrequent flyer the risk is very low. Also aviation statistics are not dominated by cabin air related accidents. Nevertheless, a bleed air based air conditioning system can be regarded as applying a fundamentally wrong systems engineering approach. Measures have to be taken. Research limitations/implications – This review study is based on references. Own measurements have not been made. Practical implications – Passengers and crew are made aware of the risk of cabin air contamination based on technical facts. Steps towards a solution of the problem are presented as they can be applied by passengers, pilots, airlines and manufacturers respectively. Social implications – Better knowledge of the problem should enable passengers and crew to maintain a firm position in the sometimes heated discussion. Originality/value – Engineering based information with a critical view on the topic seems to be missing in public. This presentation tries to fill this gap. © This work is protected by copyright The work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License: CC BY-NC-SA http://creativecommons.org/licenses/by-nc-sa/4.0 Any further request may be directed to Prof. Dr.-Ing. Dieter Scholz, MSME E-Mail see: http://www.ProfScholz.de DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 3 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Contents Aircraft Cabin Air and Engine Oil  A Systems Engineering View •Introduction •Jet Engine Oil •Cabin Comfort and Cabin Air Quality •Health and Flight Safety Implications •Certification Requirements •Air Conditioning Technology •Jet Engine •Auxiliary Power Unit (APU) •Engineering Design Principles for Air Conditioning from SAE •How much Oil Gets into the Cabin? •Carbon Monoxide (CO) in the Cabin •Engine Oil Detected on its Way into the Cabin •Measures in Aircraft Operation / Hints for Pilots •Solutions •Contact DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 4 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Introduction (Flight International 2014) ... DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 5 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Introduction ... but ... A controversial issue! (Telegraph 2017) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 6 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Jet Engine Oil (Cannon 2016) This warning was changed in 2004 (Michaelis 2012) to: "This product is not expected to produce adverse health effects under normal conditions of use ... Product may decompose at elevated temperatures ... and give off irritating and/or harmful ... gases/vapours/fumes. Symptoms from acute exposure to these decomposition products in confined spaces [aircraft cabin] may include headache, nausea, eye, nose, and throat irritation." (Exxon 2016c) TCP Material Safety Data Sheet (MSDS) FIRST AID MEASURES, INHALATION Remove from further exposure [in a fume event?]... Use adequate respiratory protection [not available for passengers!]. If respiratory irritation, dizziness, nausea, or unconsciousness occurs, seek immediate medical assistance. If breathing has stopped, assist ventilation with a mechanical device or use mouth-to-mouth resuscitation. (Exxon 2016c) Judging Jet Engine Oil Based on Warnings Given by Manufacturer DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 7 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences T = tri (3) D = di (2) M = mono (1) TOCP DOCP MOCP H3C , they are the toxic isomers. OC MC PC (Winder 2001) Tricresyl Phosphate (TCP) Jet Engine Oil TOCP: H3C DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 8 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Winder 2001 / Henschler 1958 •The 10 isomers that make up TCP are toxicologically different. •The ortho containing isomers are toxic, without ortho isomers are not toxic (Henschler 1958). •Most infamous and most studied: TOCP (tri-ortho-cresyl phosphate). •Other ortho containing isomers in TCP are more neurotoxic than TOCP: •DOCP (di-ortho-cresyl phosphates): 5 times more neurotoxic (TEF = 5), •MOCP (mono-ortho-cresyl phosphates): 10 times more neurotoxic (TEF = 10). •DOCP and MOCP are present in the engine oil in higher concentration than TOCP. •Based on concentration (Ci in ppm) and relative neurotoxicity (toxic equivalency factor, TEF) for each isomer an equivalent TOCP toxicity (TEQ) can be calculated. The base unit of the equivalent TOCP toxicity is proposed to be that of 1 ppm (1mg/l) of TOCP in the oil. TEQ =  Ci .TEFi . •Winder calculates this equivalent TOCP toxicity, considering the presents of all ortho isomers: TEQ for Mobil Jet Oil II: 30730 (The TEQ of this oil would be less than 1 if only TOCP would be present and no other ortho isomers! Therefore, ignoring the DOCP and MOCP content of the oil yields highly inaccurate results.) TEQ for Mobil 291: 17606 Jet Engine Oil TCP Toxicity Basics DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 9 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Henschler 1958 •TCP toxicity is found from animal poisoning with hens and cats. •Results obtained from these test animals can be applied to humans (with caution). •TOCP acts on the peripheral nerves and causes predominantly atonic peripheral paralysis. •MOCP and DOCP act rather on the brain and on the spinal cord. This leads to spastic paralysis. •If the content of TOCP, DOCP, and MOCP is known, calculation of TEQ is directly possible (see previous page). •If only the total ortho cresyl (OC) content q in the TCP is known, the toxic eqivalency factor, TEF can be calulated based on a purely statistical distribution of the 10 isomers (as Henschler shows). It is easy to understand: •At 0% of OC neither of MOCP, DOCP, nor TOCP are present: TEF = 0 •At 100 % of OC only TOCP would be present and TEF = 1 by definition. •The theoretical formula (blue) is with TEF(TOCP) = 1: •According to Henschler this curve needs to be adapted to fit his experimental results (red). An equation to fit this experimental curve would be (purpel): valid for q < 0,13 and can be applied to typically low OC content. Jet Engine Oil TCP Toxicity Basics qqqTEF 304516 23  2 330qTEF  DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 16 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Cabin Comfort and Cabin Air Quality – Health and Flight Safety Implications – Certification Requirements (A350 XWB News 2012) VOC: Volatile Organic Compounds are (organic chemicals – i.e. including carbon) contained in many products and can be released from these products into the surrounding air. Regulations limit VOCs. SVOC: Semi-Volatile Organic Compound (Eurofins 2017) Cabin Air Quality Cabin Comfort DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 17 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences only considered here is: ... of air contamination (EASA 2017a) Cabin Comfort and Cabin Air Quality – Health and Flight Safety Implications – Certification Requirements DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 18 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Health Effects from Indoor Air Pollutants may be experienced soon after exposure or, possibly, years later: •Long-term heath effects: •to passengers •to crew => occupational health (OH) => CS 25.831 usually related to Time-Weighted Average (TWA) Permissible Exposure Limits (PEL) •Immediate health effects: •to passengers •to cabin crew •to cockpit crew => flight safety implications can lead to: injury or death of •passenger •crew => CS 25.1309 Cabin Comfort and Cabin Air Quality – Health and Flight Safety Implications – Certification Requirements (Eurofins 2017, EASA CS-25) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 19 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Long Term Health Effects – Occupational Health ? Cabin Comfort and Cabin Air Quality – Health and Flight Safety Implications – Certification Requirements EASA CS-25: CS 25.831 Ventilation (a) Each passenger and crew compartment must be ventilated ... to enable crewmembers to perform their duties without undue discomfort or fatigue. (b) Crew and passenger compartment air must be free from harmful or hazardous concentrations of gases or vapours. In meeting this requirement, the following apply: (1) Carbon monoxide concentrations in excess of one part in 20000 parts of air [50 ppm] are considered hazardous. For test purposes, any acceptable carbon monoxide detection method may be used. (2) Carbon dioxide concentration ... "EASA is of the opinion ... only applicable for ... CO and CO2" Remark: EASA's interpretation of certification rules: The cabin is allowed to be contaminated with other substances! "The BFU is of the opinion that 'harmful concentration' should be interpreted ... to mean that health impairments (including long-term) through contaminated cabin air should be eliminated." "The BFU is of the opinion that a product [aircraft] which has received a type certificate by EASA should be designed in a way that neither crew nor passengers are harmed or become chronically ill." Bundesstelle für Flugunfalluntersuchung German Federal Bureau of Aircraft Accident Investigation (BFU 2014) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 20 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Cabin Comfort and Cabin Air Quality – Health and Flight Safety Implications – Certification Requirements Immediate Health Effects – Flight Safety Implications? EASA CS-25: CS-25.1309(b) The aeroplane systems and associated components, considered separately and in relation to other systems, must be designed so that (1) Any catastrophic failure condition (i) is extremely improbable; and (ii) does not result from a single failure; and (2) Any hazardous failure condition is extremely remote; and (3) Any major failure condition is remote. EASA CS-25: CS-25.1309 / AMC: System Design and Analysis The following definitions apply to the system design and analysis requirements of CS 25.1309 Error: An omission or incorrect action by a crewmember or maintenance personnel, or a mistake in requirements, design, or implementation. Failure: An occurrence, which affects the operation of a component, part, or element such that it can no longer function as intended, (this includes both loss of function and malfunction). Note: Errors may cause Failures, but are not considered to be Failures. It was assumed, arbitrarily, that there are about one hundred potential Failure Conditions in an aeroplane [one in each of an assumed number of 100 systems], which could be Catastrophic. The CS-25 airworthiness standards are based on ... the fail-safe design concept ... The fail-safe design concept uses the following design principles: (i) Designed Integrity and Quality, including Life Limits, to ensure intended function and prevent failures. (v) Failure Warning or Indication to provide detection. (xi) Error-Tolerance that considers adverse effects of foreseeable errors during the aeroplane's design, test, manufacture, operation, and maintenance. DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 21 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Cabin Comfort and Cabin Air Quality – Health and Flight Safety Implications – Certification Requirements Flight Safety Implications? "In regard to the demonstration of compliance in accordance with CS-25.1309, EASA classifies the impairment of the capability to act (without incapacitation) as "Major"[< 10-5]. This means, however, that these events, with a certain frequency of occurrence, are accepted. The social acceptance of this value cannot be assessed ..." (BFU 2014) Remarks: 1. EASA's classification is wrong. "impairment" is "Hazardous" (< 10-7) and demands less frequent occurence by a factor of 100. 2. CS-25.1309 is meant for failure cases of statistical nature and not as an excuse for known and deliberate negligence in design! (see next page for details) EASA CS-25: CS-25.1309(b) / AMC DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 22 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Cabin Comfort and Cabin Air Quality – Health and Flight Safety Implications – Certification Requirements Interpretation of AMC 25.1309 with respect to Bleed Air from Jet Engines EASA CS-25: AMC 25.1309: System Design and Analysis The aeroplane systems and associated components, must be designed so that (1) Any catastrophic failure condition (2) (ii) does not result from a single failure Attention: A single seal failure has the potential to cause a catastropic failure due to pilot incapacitation. This is in contradiction to CS-25. EASA CS-25: AMC 25.1309: System Design and Analysis The CS-25 airworthiness standards are based on ... the fail-safe design concept ... The failure probabilitiy of a system is calculated based on the Mean Time Between Failure (MTBF) of its components. The components are normally functional, but may fail randomly. 100% reliability of components does not exist. This is much in contrast to the situation of bleed air taken from the engine which is systematically contaminated (to some extend) with engine oil. This is not a failure (for which a probability could be calculated), but a design error (violating existing SAE design conventions). EASA CS-25: AMC 25.1309: System Design and Analysis The fail-safe design concept uses the following design principles: (i) Designed Integrity and Quality (v) Failure Warning or Indication to provide detection. (xi) Error-Tolerance that considers adverse effects of foreseeable errors during the aeroplane's design, test, manufacture, operation, and maintenance. But with bleed air from jet engines: (i) Design integrity is not given! (v) Failure Warning in case of cabin air contamination is not provided! Furthermore: (xi) Known deficiencies are not allowed. The system has to be error-tolerant to yet UNKNOWN design errors that have to be envisaged because it is a known fact in life that errors do occur (and as such they are forseeable). The system's error-tolerance is compromized, if it has to cope with already known design errors that are not rectified out of negligence relying on the systems error-tolerance. DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 23 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Cabin Comfort and Cabin Air Quality – Health and Flight Safety Implications – Certification Requirements Flight Safety Implications Due to Cabin Air Contamination? There have been several (much debated) critical flight instances, but so far (luckily) no death (due to flight safety implicatons) and no hull loss. Compare e.g. with the issue "Degraded Manual Flying Skills" (Flight International 2017) From 2000 to 2017: •19 fatal accidents •2012 fatalaties Remark: There are certainly several issues in aviation of more pressing nature than "cabin air quality / contamination", however, the suffering of individuals (potentially / probably) due to cabin air contamination can not be ignored (may it just be for ethical reasons), because the underlying deficits in aircraft system design are a fact (see below) and need to be solved. DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 24 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Air Conditioning Technology (dm/dt)in (dm/dt)out low pressure "normal" pressure 1) compress the air 2) cool the air => Temperature Control 3) release the air => Pressure Control: out > in: pressure goes down in > out: pressure goes up Air Conditioning Basics Temperature Control, Pressure Control, Ventilation Adapted from (NRC 2002) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 25 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Air Conditioning Technology Air Conditioning with Recirculation Adapted from (NRC 2002) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 32 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences SAE about the Design of the Air Conditioning Pack Air Conditioning Technology SAE ARP 85E: Air Conditioning Systems for Subsonic Airplanes 5.2.2.d:. Bearings: Air cycle machines typically use precision angular contact ball bearings or air bearings. In either case, the bearing system should be self-contained, requiring no external oil supply or external pressurizing air source. DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 33 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Engine Overview (Wikipedia 2017a) Jet Engine DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 34 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Engine Overview Jet Engine Engine Alliance GP7000 (Assuntos Militares 2013) bearing (example) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 35 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Jet Engine Bearing Jet Engine (Exxon 2016b) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 36 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Quotes from: Exxon Mobile (2016a): “Jet Engine Oil System – Overview” with remarks: •"The scavenged oil flow is slightly lower than the supply flow due to normal oil consumption through the deoiler, oil seals, and oil leaks." (Remark: Oil escapes also from the seals) •"Therefore, a large amount of air is carried by the scavenge oil and must be removed through a de-aerator when entering the tank." (Remark: Seals do not seal but allow large amounts of air to enter the seals. If pressure in the compressor is low compared to pressure in the oil system i.e. low p, oil can escape from the seals.) (Exxon 2016a) Engine Air and Oil System based on: Exxon 2016a de-aerator and vent overboard DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 37 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Engine Air and Oil System Jet Engine based on: Exxon 2016b (oil) (air & oil) (oil & air) & oil & oil (oil & air) Quotes from: Exxon Mobile (2016b): “Jet Engine Oil System – Bearing Sump Lubrication” with remarks: "Oil sumps are a part of the oil circuit, where oil must remain. Leakage outside the oil system could pollute the air bleeds" "The pressure inside the oil sump must always be lower than the pressure outside the sump." "Pressurized air is ... injected between two labyrinth seals ... It then flows across the oil seals, preventing oil seepage past the oil seals." "Air mixes with part of the oil ... making an oil mist ... the vent air, ... has to be discharged overboard [after going] through an air/oil separator [the de-aerator]." "The vent tube must remain wide open to avoid leaks due to low p through the oil seals." (Remark: Accordingly, prerequisite for leakage is not necessarily a negative  p – instead, a low  p is sufficient for leakage. It can happen e.g. with partial blockage of the vent tube.) "The double wall around the sump ... applies to sumps ... in the hot areas." "Some designs do not use double walls, particularly when carbon seals are used." "In many applications, oil that crosses the oil seal is collected and routed by a tube to an aircraft drain collector that is inspected from time to time and is used as a seal monitoring tool." Remarks: 1.) When a double wall design is used, 'air with some oil' is in the so called 'dry cavity' (some of this oil is drained). Air with a low oil content is leaving the 'dry cavity' into the compressor (see picture). 2.) When double walls are used, oil leaks from the inner seal to the 'dry cavity'. Therefore: When only a single wall design is used, air and oil leak directly into the compressor. 3.) Conclusion: In both cases: Jet engine seals leak oil by design. Read more on this topic: Michaelis 2016a and Michaelis 2016b DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 38 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Types of Jet Engine Seals Jet Engine air oil (Rolls Royce 2015) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 39 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Jet Engine Types of Jet Engine Seals Brush Seal e.g. on PW1000G geared turbo fan (DGLR 2014) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 40 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences APU Description (A340 FCOM) Overview Auxiliary Power Unit (APU) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 41 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences (A320 GENFAM) •An Auxiliary Power Unit (APU) is a gas turbine engine. •An APU will need some form of lubrication (e.i. oil). •Lubrication needs will be smaller than in aircraft engines, but the APU otherwise experiences the same problems with oil leakage as described for the engine. Bearings and Load Compressor Auxiliary Power Unit (APU) APU GTCP36-300 DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 48 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Some air (and oil) gets tapped off through the bleed ports. The oil concentration in the bleed flow is the same as the oil concentration in the compressor, if uniform oil distribution is assumed in the compressor. Furthermore, the oil concentration in the cabin is the same as the oil concentration in bleed flow (after steady state is reached), because cabin air is conditioned bleed air (ignoring filtered recirculated cabin air at this point). The oil concentration is calculated from the oil mass flow rate and air mass flow rate together with (1). Note, air density, has to be considered, when oil concentration is presented as mass of oil (in g) per volume of air (m³). How much Oil Gets into the Cabin? Derivation The mass flow through the core of the engine can be calculated from the mass flow through the engine's inlet and the engine bypass ratio . core bypass m m     corebypasstotal mmm   11   core bypass core total m m m m     1   total core m m   Oil entering the compressor through the bearing seals is a fraction, xseal of the total oil consumption (oil mass flow rate). Only oil from bearings upstream of the bleed ports can enter through the bleed ports. The fraction of this oil is xbear,up and the oil mass flow rate approaching the bleed ports in the compressor is sealupbearoilcompoil xxmm ,,   (1) (2) )1( ,, ,,   total compoil core compoil cab caboil cab caboil m m m m m m m m       )1( )( , ,    CRCRtotal compoil cabcab caboil hV m V m   )1( )( )( , ,    CRCR cabcab total compoil cab caboil h h V m V m   (3) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 49 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Cruise speed is a function of cruise Mach number, MCR and speed of sound, a(hCR), which is a function of cruise altitude, hCR . How much Oil Gets into the Cabin? Derivation Air density,  has to be calculated from the International Standard Atmosphere (ISA) as a function of the respective altitude, h. Cabin altitude, hcab has to be less than 8000 ft (EASA CS-25). Often hcab = 8000ft in cruise and as such  cab = 0.963 kg/m³. Cruise altitude hCR may be set to 11 km (tropopause) for passenger jets, if no other value is given and as such  CR = 0.364 kg/m³ . The total flow into all engines of the aircraft is calculated from engine inlet area Seng, number of engines neng and cruise speed VCR . (4) (5) CRengengtotal VnSV   )( CRCRCR haMV  m/s295a km11 CR h for with Equations 3 with Equations 2 and 4 (making use of 5) yields   1 )( , ,    CR cab CRCRengeng sealupbearoil cab caboil haMnS xxm V m 0 0 )( T T aha CR  K 216,65with 0 ThLTT CR L = 1.9812 . 10-3 K/ft, T0 = 288.15 K, a0 = 340.29 m/s DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 50 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences S 1,73 m 5.7 0.6 How much Oil Gets into the Cabin? Example Calculation 17   1 )( , ,    CR cab CRCRengeng sealupbearoil cab caboil haMnS xxm V m xseal = 1 % (conservative estimate!) 5 0.6 both engines, neng = 2 0.1673 DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 51 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Ʃ aromatic hydrocarbons, comparison of different studies (median); * highest values from three investigated airlines (EASA 2017a) How much Oil Gets into the Cabin? Example Calculation Compared with Measurements Calculated: In-flight measurements with conservative estimate: xseal = 1 % 17 DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 52 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Carbon Monoxide (CO) in the Cabin CO Basics Michaelis 2010 "Carbon monoxide (CO) may be produced as a by-product of incomplete combustion and may be generated due to thermal decomposition of contaminants entering the bleed air supply system, such as oil hydraulic fluids or deicing fluids. The CO concentration generated will be dependent upon many factors, such as airflow, the quantity of the contaminant, and the temperature of the bleed air and surfaces in contact with the contaminant." "Carbon monoxide is an odourless, colourless and toxic gas. ... it is impossible to see, taste or smell the toxic fumes." "The effects of CO exposure can vary greatly from person to person depending on age, overall health and the concentration and length of exposure. Acute symptoms from CO include headaches, confusion, dizziness, nausea, weakness and unconsciousness." "Long term (chronic) exposure to Iow levels of carbon monoxide may produce heart disease and damage to the nervous system. Longer term effects of CO are now known to result in brain damage and cognitive impairment ... Exposure of pregnant women to carbon monoxide may sause low birth rates and nervous system damage to the offspring." DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 53 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences CO Related: CS-23: Certification Specifications: Normal ... and Commuter Category Aeroplanes (and CS-25: Certification Specifications: Large Aeroplanes) EASA CS-23: CS 23.831 Ventilation (a) Each passenger and crew compartment must be suitably ventilated. Carbon monoxide concentration may not exceed one part in 20000 parts of air [50 ppm]. (b) For pressurised aeroplanes, the ventilating air in the flight crew and passenger compartments must be free of harmful or hazardous concentrations of gases and vapours in normal operations and in the event of reasonably probable failures or malfunctioning of the ventilating, heating, pressurisation, or other systems and equipment. EASA CS-23: CS 23.1309(b) The design of each item of equipment, each system, and each installation must be examined ... to comply with the following additional requirements: ... (2) When systems and associated components are considered separately and in relation to other systems – (i) The occurrence of any failure condition that would prevent the continued safe flight and landing of the aeroplane must be extremely improbable; and (ii) The occurrence of any other failure condition that would significantly reduce the capability of the aeroplane or the ability of the crew to cope with adverse operating conditions must be improbable. Remark: A table relating Probability of Failure and Effect of Failure – like the one in AMC 25.1309(b) – does not exist here. EASA CS-23: CS 23.1309(b)(3) Warning information must be provided to alert the crew to unsafe system operating conditions and to enable them to take appropriate corrective action. ---------------------------- EASA CS-25: CS-25.1309(c) Information concerning unsafe system operating conditions must be provided to the crew to enable them to take appropriate corrective action. A warning indication must be provided if immediate corrective action is required. (For an extensive discussion of CS-25 with respect to bleed air see "Immediate Health Effects – Flight Safety Implications".) Carbon Monoxide (CO) in the Cabin DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 54 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences CO Related Accidents with General Aviation (GA) Aircraft CO detectors using electrochemical sensors may be the most suitable technology for use at this time in a GA environment. Electrochemical CO detectors available on the market that are likely suitable for use in a GA environment range in price from 175 US$ to 200 US$, possess good battery life (2000 h to 2600 h), and have quick response times (12s to 35s). Collectively considering the advantages and limitations of the various CO detector technologies, electrochemical sensors appear to be the most suitable for a GA environment due to their relatively high accuracy, quick response time, inherent immunity to false alarms, and low power consumption. The instrument panel appeared to be the best location for the placement of CO detectors. NTSB 2004 The National Transportation Safety Board recommends that the Federal Aviation Administration [should] require the installation of carbon monoxide (CO) detectors ... in all single-engine reciprocating-powered airplanes with forward-mounted engines and enclosed cockpits ... (A-04-28) Remark: But the FAA did not require mandatory CO detectors. AOPA 2004 According to the Aircraft Owners and Pilots Association (AOPA), mandatory carbon monoxide (CO) detectors in piston-powered single-engine aircraft would do little to lower the general aviation (GA) accident rate. AOPA only found "just" one accident per year due to CO (in the USA). The low-cost (10 US$) opto-chemical CO detector cards found in many aircraft are usually not promptly replaced when past their recommended useful life and are most effective only when very high levels of CO enter the cockpit. FAA 2009a As much as 62 CO related accidents were identified between 1962 and 2007 from a reviewed of the National Transportation Safety Board (NTSB) database (1,4 per year in the USA alone). Although there are more reasons for CO poisoning, the most problematic component is the heat exchanger in the heating/exhaust system. Fresh air for the cabin moves along the surface of the muffler. Any crack or hole in the muffler can allow exhaust gas with CO to contaminate the cabin air. To improve the situation, maintenance practice (crack finding), lifetime limits for mufflers, and use of a suitable CO detector, would serve as a method to prevent CO exposure in GA aircraft. None of this is demanded by FAA. Carbon Monoxide (CO) in the Cabin DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 55 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Carbon Monoxide (CO) in the Cabin CO Detectors FAA 2017 A Technical Standard Order (TSO) is a minimum performance standard for specified materials, parts, and appliances used on civil aircraft. When authorized to manufacture a material, part, or appliances to a TSO standard, this is referred to as TSO authorization. Receiving a TSO authorization is both design and production approval. Receiving a TSO Authorization is not an approval to install and use the article in the aircraft. It means that the article meets the specific TSO and the applicant is authorized to manufacture it. Remark: The existence of a TSO does not mean this equipment has to be used. FAA 2009b TSO C48a "Carbon Monoxide Detector Instruments" applies to equipment that detect CO and emits a warning when levels become dangerous. The TSO points to SAE AS-412A for most technical details. EASA 2003 "European Technical Standard Orders" contains ETSO C48: "Carbon Monoxide Detection Instruments" which points for further requirements to SAE AS-412A: "Carbon Monoxide Detector Instruments". SAE AS-412 "Carbon Monoxide Detector Instruments". The Aeronautical Standard covers the basic type of carbon monoxide detector instrument used to determine toxic concentrations of carbon monoxide by the measurement of heat changes through catalytic oxidation. There are four types of CO sensors available: •Opto-chemical (color spot, blob): A pad of a colored chemical which changes color upon reaction with carbon monoxide. •Biomimetic (colorimetric): An LED shines through a colored chemical detector onto a photocell. •Electrochemical: An electrochemical cell consisting of a container, two electrodes and electrolyte. •Semiconductor: Tin dioxide on a ceramic base heated to 400 °C. See also SAE AS-412A. Example of a digital electrochemical CO detector: •Display range: 7 PPM to 100 PPM •Dimensions: diameter 6cm, thickness: 4 cm •Powered by: 2 AAA batteries AEROMEDIX "CO Experts ULTRA" AEROMEDIX Keychain Aviation Carbon Monoxide Detector DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 56 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences CO in Passenger Aircraft Cabins The CO level in normal operation is much lower than the limit of 50 ppm (specified in CS 23.831 and CS 25.831). Failure cases did not occur during these measurements. CO: 1 mg/m³ = 0.87 ppm (at 25°C) (EASA 2017a, p. 73) EASA 2017a, p.74 Normal Situation Failure Case: Fume Event US Airways Flight 432 Phoenix to Maui, B757, 17.09.2010 (Aviation Herald 2010). Video on: https://goo.gl/4wAwtZ EASA 2017b (p. 75 - 77) "Until the oil has reached 180˚C hardly any emission of CO arises. However, it appears that following the increase of temperature of the oil from 180°C to 375˚C, CO emissions are formed due to incomplete combustion of the oil." "[At 375°C] the CO concentration is increasing severe[ly]." "It is not meant that results of our work can be up-scaled, neither be related to typical aircraft ... [nor] engines." Air in the compressor reaches more than 500°C. So, we know much CO is present in the cabin during a Fume Event. The exact concentration is only known when measured during the event. Therefore, pilots should by all means carry their personal CO detector and make decisions accordingly! Carbon Monoxide (CO) in the Cabin DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 57 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Conclusions Carbon Monoxide / Bleed Air / CO Detectors / CO-Related GA Accidents / CS-23 When comparing the text of CS-23 and CS-25 with respect to §831(a)(b) and §1309(3)(b) / §1309(c) it is found that the legal situation is almost the same for general aviation aircraft (certified in accordance with CS-23) and for large aeroplanes (certified in accordance with CS-25). CO detectors have NOT been made mandatory (neither for CS-23 nor for CS-25 aircraft). It only has become common practice by owners of piston engined small aircraft to fit inexpensive (unfortunately also quite ineffective) opto-chemical ("color spot") CO detectors. As long as pilots due not include these detectors regularly into their instrument scan they are of no use. Usually high pilot workload especially in demanding flight situations will most probably not allow them for scanning the CO detector and the detectors color change will pass unnoticed. It is inappropriate to compare a) the situation (related to cabin air contamination due to CO) of single piston engined aircraft (heat exchanger) with b) the situation (related to cabin air contamination due to bleed air) of jet powered passenger aircraft (bleed air). We can only learn here that a large resistance exists (in the aviation industry) to changes of standard legal practice (that demands additional money or effort). Pilots concerned about cabin air contamination should no longer wait for legal / manufacturer's / airline's action. Instead, pilots should carry their personal digital CO detector on board and should take safety precautions in accordance to measurements from these devices. Acute symptoms of CO and TCP poisoning have some similarity. CO as well as TCP poisoning can lead to pilot incapacitation. The situation is aggravated by the many other dangerous constituents of pyrolized engine oil. It is clear that also larger quantities of oil can get into the cabin during engine malfunctions (as seen in fume events). Elevated readings from a CO detector should be taken as indicative of a more general cabin air problem endangering the pilot's level of alertness. Carbon Monoxide (CO) in the Cabin DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 64 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Derivation: Direct Venting of the Cabin in 10000 ft Derivation of Equations (see considerations on previous page) •cruise speed in 10000 ft, V_10k (TAS) •Mach number in 10000 ft, M_10k •range in 10000 ft, R_10k Calculating the reduced range: Measures in Aircraft Operation / Hints for Pilots DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 65 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences •If the oil gets pyrolyzed the situation gets worse, certainly not much better. •In the same way as decades ago: Engine oil should not get into the aircraft cabin. •NYCO offers a jet engine oil without TCP: TURBONYCOIL 600 (Petro-Canada 2017) Harzard Codes of the "Phenol, isopropylated, phosphate (3:1)" (DURAD 150) are: H361: Suspected of damaging fertility or the unborn child if swallowed. H411: Toxic to aquatic life with long lasting effects. R48/22: Harmful: danger of serious damage to health by prolonged exposure if swallowed. R62: Possible risk of impaired fertility. R63: Possible risk of harm to the unborn child. Also NYCO's oil is not without risk. Solutions Engine Oil Developments •The extrem working environment of a jet engine needs special additives. Unproblematic additives have not been found so far. •TOCP content has been much reduced over last decades. TOCP seems not to be used deliberately any more, but can be in the oil occasionally in very small quantities. •Toxic DOCP and MOCP are not properly reported. It is unlikely that good news is hidden. It is evident that air crew showed signs of TCP poisoning. If in doubt caution is mentatory. DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 66 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Solutions Sensors to Detect TCP and VOC Measurement of hydrocarbon content (ppmand ppb-level) a) Measuring the (unaltered) bleed air from an APU at HAW Hamburg, b) Checking the sensitivity of the equipment with pyrolyzed aviation fluids. Gröger und Obst GmbH, 2014. The equipment is still too large (blue rack) for easy integration into the aircraft. See also: Reiss 2016. aerotracer (Airsense 2017) •offered for sale. •detects 15 substances: grease, liquid, gas: engine oils, de-icing fluids, hydraulic fluids, corrosion inhibitors, glue, heat transfer fluid, kerosene, ... •power supply: 110 to 240 VAC; 30 W or rechargeable battery (operating time 4 hrs). •electronics: graphical display, Mini SD Card. VN Aerotoxic Detection Solutions (VN-ADS) (Aircraft Interiors 2017) •prototypes are tested. •Company claims to have the world's first real-time detector of poisonous compounds in aircraft cabins. (Aircraft Interiors 03/2017) •Mono Fibre Optical Measuring Technology (MOMT) ... have demonstrated the capability to detect Tricrysel Phosphate (TCP) and other Volatile Organic Compounds (VOCs) and Semi Volatile Organic Compounds (SVOCs) in real time. DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 67 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Solutions Filters to Remove TCP and VOC Pall has several treetment solutions for cabin air on offer: •Carbon Filter •Photo Catalytic Oxidization (with UV light) •Catalytic Converters (oxidization). Location is possible: •upstream of the pack, •downstream of pack, •at recirculation filter (reduced efficiency compared to a filter in line with the pack – see next page) Pall offers Odour/VOC Removal Filters •The carbon adsorbent is effective at adsorbing volatile organic compounds (VOC). Test results have shown a removal efficiency of 65% ... 73% when challenged with TCPs in the gaseous phase. Carbon adsorbents have some effectiveness with ozone but not with carbon monoxide (CO). Removal of these compounds from the cabin air is by adsorption on to carbon based filters. (Pall 2011) Application of carbon filters: •33 HEPA-Carbon filters have been added (so far) to A321 aircraft at Lufthansa Group. (Lufthansa 2017) •Pall carbon filters are installed on the B757 cargo fleet of DHL. Carbon filters are installed in place of the air ducts leading to the cockpit. EASA issued an STC for the installation. (EASA 2010) Such a filter is recommended to protect against chemical weapons, but it is (so far) not intended to be use on aircraft. Schematic of carbon Filter (Pall 2011) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 68 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences filtration rate, xfil Example calculation: •The Pall carbon adsorbent is effective at adsorbing volatile organic compounds with a removal efficiency of 65% ... 73% when challenged with TCPs in the gaseous phase. (Pall 2011) •The A320 has a recirculation rate of 50%. •With a filtration rate, xfil = 0,7 and a recirculation rate, xre = 0,5 the filter reduces the incoming concentration to 58,9%. Solutions But: How Efficient are Filters in the Recirculation Path?   refil re incont cabcont xx x x x   11 1 , , re incont cabcont fil x x x x   1 :1for , , DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 69 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Solutions out m  in m  tot m  outrere mm ,   in m  inre m,  filter Derivation: Efficiency of Filters in the Recirculation Path Adapted from (NRC 2002) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 70 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Solutions out m  in m  tot m  outrere mm ,   in m  inre m,  filter   refil re incont cabcont xx x x x   11 1 , , re incont cabcont fil x x x x   1 :1for , ,      reincontrefilcabcont xxxxx  111 ,, Derivation: Efficiency of Filters in the Recirculation Path Adapted from (NRC 2002) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 71 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Prof. Van Netten invented this "VN-Sampler". It is not an in situ measurement device, but a means to collect the air in a fume event for later detailed analysis in a laboratory on the ground. The device is FAA approved. (Van Netten 2008) Solutions Air Sampler for Later Air Analysis DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 72 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Solutions Cabin Pressurization Principles and Solutions Overview •First Jet Aircraft used a "blower" or "turbocompressor" (TC). The TC is the coupling of a turbine with a compressor. Bleed air from the engine compressor drives the TC turbine. The TCs compressor compresses outside air to meet the pressurization requirements of the cabin. The hot compressed air needs to be cooled. This can be done with a "vapor cycle system" (as known from the refrigerator). •Current Aircraft make use of bleed air directly. It is compressed so much that it contains enough energy to also drive the pack that cool the bleed air down to temperatures considerably less than 0°C. •The Boeing 787 uses electrical power to drive an electric motor to drive a compressor. The energy is extracted from the engine by means of shaft power driving a generator. No bleed air is used. The engine is "Bleed Free". (Michaelis 2010) Solution? Problem? Solution! DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 73 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences Solutions Aircraft with Turbocompressors Solution DC-8? •Bleed air was used to power a turbocompressor, which compressed the ram air to the proper pressure. That air was cooled by a Freon vapor compression-cycle air conditioner for temperature control before being distributed to the cabin. The arrangement was heavy, expensive, and inefficient because of the inefficiencies of the turbocompressor (E. Marzolf, retired, Douglas Aircraft Co.) (NRC 2002) •Even more important was the high amount of maintenance that the systems required (R. Kinsel, retired, AlliedSignal) (NRC 2002) •The inlets on the front of the DC8 are for the 4 turbocompressors [TC's] used to pressurize the cabin. The top and bottom inlets feed the turbo compressors. [The middle inlet] feeds heat exchangers to cool the compressed air from the TC's. The bleed air from the engines which is used to spin the turbo compressors exhausts overboard from the vent located on the side of the fuselage [only a little] aft [and a little higher]. (Jetpilot 2001) DC-8 (Airline Ratings 2017) •"The TC's on the DC8 were extremely noisy in the cockpit, and had a tendency to have uncontained [rotor] failures which scared the shit out of you as the pieces had a tendency to rip into the cockpit on occasion. To find the condition of a TC on the preflight one only had to look at the TC exhaust duct and find how much oil from the bearing case had leaked past the seal and run all over the fuselage. I never saw a TC that didn't leak. They also made strange noises notifying you of their impending doom." "TC's spool up to about 13000 RPM in about 2 seconds." (Jetpilot 2001) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 80 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences References Aircraft Interiors 2017 Aircraft Interiors: News: World's First Aircraft Cabin Monitor for Toxic Air Announced, UKIP Media & Events, 2017. – URL: http://www.aircraftinteriorsinternational.com/news.php?NewsID=84385 Airlineratings 2017 Airline Ratings, 2017. – URL: http://image.airlineratings.com/articles/DC-8%20DWDcropfb.jpg Airliners 1999 Discussion on www.airliners.net, 1999. – URL: http://www.airliners.net/forum/viewtopic.php?t=72326 Airsense 2017 Airsense Analytics: aerotracer - Supervision in Aviation Industry, Leaflet, 2017. – URL: http://www.airsense.com/sites/default/files/airsense_aerotracer.pdf AOPA 2004 AOPA: Mandatory Carbon Monoxide Detectors Would Have Little Effect on Safety CO Related Accidents with General Aviation (GA) Aircraft, 2004. – URL: https://www.aopa.org/news-and-media/all-news/2004/june/30/mandatory-carbonmonoxide-detectors-would-have-little-effect-on-safety Aviation Herald 2010 Aviation Herald: Incident: US Airways B752 over Pacific on Sep 17th 2010, Smoke in Cockpit, 2010. – URL: http://avherald.com/h?article=4311269d B737 AMM Boeing: B737 – Aircraft Maintenance Manual (AMM) DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 81 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences References BFU 2014 Bundesstelle für Flugunfalluntersuchung (BFU): Study of Reported Occurrences in Conjunction with Cabin Air Quality in Transport Aircraft, 2014 (BFU 803.1-14). – URL: https://www.bfu-web.de/EN/Publications/Safety%20Study/Studies/140507_Fume_Events.pdf?__blob=publicationFile Boeing 2007 Sinnett, Mike: 787 No-Bleed Systems: Saving Fuel and Enhancing Operational Efficiencies. In: Boeing: AERO, 2007, No. 4, Art. 2, pp. 6-11. – URL: http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_07/article_02_1.html Cannon 2016 Cannon, Frank: Aircraft cabin air contamination and aerotoxic syndrome – A review of the evidence. In: Collegium Basilea: Nanotechnology Perceptions, Vol. 12 (2016), pp. 73-99, https://doi.org/10.4024/N08CA16A.ntp.12.02. – Download: URL: http://skybrary.aero/bookshelf/books/3594.pdf De Nola 2008 De Nola, G.; Kibby, J.; Mazurek, W.: Determination of Ortho-Cresyl Phosphate Isomers of Tricresyl Phosphate Used in Aircraft Turbine Engine Oils by Gas Chromatography and Mass Spectrometry. In: Journal of Chromatography A, Vol. 1200, No. 2, pp. 211-216, 25 July 2008, https://doi.org/10.1016/j.chroma.2008.05.035 DGLR 2014 Deutsche Gesellschaft für Luftund Raumfahrt (DGLR): Pratt & Whitney setzt für Getriebefan-Antriebe auf Bürstendichtungen. In: Luftund Raumfahrt, Special Issue: "A320neo – Special", 2014 EASA 2003 European Aviation Safety Agency (EASA): European Technical Standard Orders, contains ETSO C48: "Carbon Monoxide Detection Instruments", 2003. – URL: https://www.easa.europa.eu/system/files/dfu/CS-ETSO.pdf DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 82 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences References EASA 2010 European Aviation Safety Agency (EASA): Supplemental Type Certificate 10030229 (B757), 2010. – URL: http://bleedfree.eu/wp-content/uploads/2015/10/B757-air-filter-EASA-STC.pdf EASA 2017a European Aviation Safety Agency (EASA): CAQ – Preliminary Cabin Air Quality Measurement Campaign, 2017. – URL: https://www.easa.europa.eu/document-library/research-projects/easarepresea20144, Project partners: Fraunhofer ITEM, Hannover Medical School (MHH), Lufthansa Technik AG / Deutsche Lufthansa AG, Condor Flugdienst GmbH, British Airways EASA 2017b European Aviation Safety Agency (EASA): AVOIL – Characterisation of the Toxicity of Aviation Turbine Engine Oils after Pyrolysis, 2017. – URL: https://www.easa.europa.eu/document-library/research-projects/easarepresea20152, Project partners: The Netherlands Organization for Applied Scientific Research (TNO), National Institute for Public Health and the Environment (RIVM), Institute for Environmental Studies (IVM), Institute for Risk Assessment Sciences (IRAS) EASA CS-23 European Aviation Safety Agency (EASA): Certification Specification (CS-23) "Normal, Utility, Aerobatic and Commuter Aeroplanes", 2012. – URL: https://www.easa.europa.eu/certification-specifications/cs-23-normal-utility-aerobatic-and-commuter-aeroplanes EASA CS-25 European Aviation Safety Agency (EASA): Certification Specification (CS-25) "Large Aeroplanes", 2017. – URL: https://www.easa.europa.eu/certification-specifications/cs-25-large-aeroplanes DGLR, RAeS, VDI, ZAL, HAW Hamburg, VC, UFO Dieter Scholz: Aircraft Cabin Air and Engine Oil 27.04.2017, Slide 83 Aircraft Design and Systems Group (AERO) Hochschule für Angewandte Wissenschaften Hamburg Hamburg University of Applied Sciences References Eckels 2014 Eckels, Steven J.; Jones, Byron; Mann, Garrett; et al.: Aircraft Recirculation Filter for Air-Quality and Incident Assessment. 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