AC 39-8A Appendix D ‡ The CAAM 3 report separates the bird related events from the non-bird related events.
The two were combined for this AC.
⁰ The CAAM 1 report multi-engine data was not collected using the same categories as the CAAM 2 and CAAM 3 reports.
D-3
AC 39-8A Appendix D D.10 Failure Condition: Engine/Pylon Separations.
An engine/pylon separation is defined as a separation of the engine, with or without the strut/pylon. Events resulting from ground contact are excluded Table D-15 - Engine/Pylon Separations Engine/Pylon Separation L3 $L4 ¡L5 Total Events | Events HR | Events HR ; Events HR CAAM 1 (1982-1991) Turboprop 3: :
LBPRI 2 * HBPR 2 1.0 2 1.0 CAAM 2 (1992-2000).
Turboprop 2 LBPR 1 0.667 2 0.5 1 0.167 HBPR 2 1.0 0.333 : 1 0.333 CAAM 3 (2001-2012) Turboprop LBPR 2 0.5 1 0.5 HBPR 1 * Combined T Turboprop LBPR 10 1 0.500 0.400 1 0.100 HBPR 2 0.833 2 0.500 1 0.167 + The data is combined here for convenience. The user should review the event descriptions and definitions in the CAAM reports for relevance to the particular issue being assessed.
D-4
AC 39-8A Appendix D D.11 Failure Condition: Cowl Separation.
A cowl separation is defined as a separation of nacelle components such as inlets, cowls, thrust reversers, exhaust nozzles, tail plugs, etc. Separation of relatively small sections of skin, blow-out panels, or other small pieces that are unlikely to hazard continued safe flight and landing are excluded. Events resulting from ground contact are excluded.
Table D-16 - Cowl Separation Hazard Ratios Cowl Separation ỊLЗ İL4 :L5 Total Events ! Events | Events HR | Events HR CAAM 1 (1982-1991) Turboprop LBPR 28 * HBPR 78 1 0.01 CAAM 2 (1992-2000) Turboprop LBPR 27 1 0.04 HBPR 117 1 0.01 * CAAM 3 (2001-2012) Turboprop LBPR 17 * HBPR 96 2 0.02 * Combined t Turboprop 9 LBPR 72 1 0.014 HBPR 291 4 0.014 * † The data is combined here for convenience. The user should review the event descriptions and definitions in the CAAM reports for relevance to the particular issue being assessed.
D-5
AC 39-8A Appendix D D.12 Failure Condition: Asymmetric Thrust Reverser Deployment/Inflight Beta.
An asymmetric thrust reverser deployment/inflight beta is defined as a significant safety event wherein a thrust reverser deploys in-flight, or a propeller enters beta mode inflight (exclusive of design intent).
Table D-17 - Thrust Reverser Deploy - Inflight Hazard Ratios Thrust Reverser Deploy - Inflightt ¡LЗ İL4 :L5 Total Events | Events HR | Events HR : Events HR CAAM 1 (1982-1991) Turboprop NA NA NA NA NA NA NA LBPR 15 1 1 HBPR 20 5 * * 1‡ * CAAM 2 (1992-2000) Turboprop 5 1 2 2 LBPR * HBPR 13 2 0.23 0.08 1 0.08 CAAM 3 (2001-2012) Turboprop * 2 LBPR * * * HBPR 6 * * * † Data was not combined due to the changes in the definition across the three reports.
Note: ‡ The CAAM 1 report did not include L5 as a classification. One L4 event was re-classified as L5 in the original release of AC 39-8, and the classification is also used here.
D-6
AC 39-8A Appendix D D.13 Failure Condition: Fuel Leak.
A fuel leak is defined as a leak of fuel into the pylon or dry bay, or under the engine cowls, which could credibly lead to a fire. Leaks collected from shrouds and components and drained directly overboard by a dedicated drain were excluded from those leaks under consideration due to their lack of being fire safety concerns. Drips and seeps were also excluded. In-tank leakage was excluded.
Table D-18 - Fuel Leak Data † Data was not combined due to the changes in the definition across the three reports, the wide variety of circumstances surrounding the source of the fuel leak, and significant under-reporting of base events.
D-7
AC 39-8A Appendix D D.14 Failure Condition: Propeller System Events.
• Propeller separation and debris release. Separation of single or multiple blades, or large pieces thereof, due to blade or hub malfunction. Note that events occurring after a ground strike are included for their information on their threat to the airplane or its occupants.
• Autofeather and pitch lock. Propeller system malfunction leading to the inability to control the propeller. Control hunting is excluded as a normal product behavior.
• Propeller system malfunction recognition and response (PSMRR). A significant safety event initiating from a propeller system malfunction which, by itself, does not hazard the airplane, passengers, or crew, but is compounded by inappropriate crew response.
• Crew error. In the context of the propeller system, a significant safety event caused by a propeller system malfunction or improper operation that was caused by an inappropriate crew action, excluding sabotage, gross negligence, and suicide (e.g., operation in beta mode in violation of operating instructions). Also not included are events where inappropriate crew action causes a propeller system malfunction through very indirect means such as flying the airplane into the ground or running the airplane into equipment on the taxiway and runway. This category has previously been referred to as Propulsion System Malfunction plus Inappropriate Crew Response – PSM+ICR.
• Propeller gearbox and attachment. A propeller gearbox and attachment failure are defined as an in-flight separation of a propeller assembly as the result of a propeller gearbox or attachment malfunction.
• Loss of control (negative thrust). The loss of control is defined as a propeller system malfunction leading to negative thrust (high drag).
• Other. A significant propeller-related safety event not included in the propeller categories discussed above and for which the initiating cause(s) is unique to one HL 3 or 4 event in the reporting period.
D-8
AC 39-8A Appendix D Table D-19 - Propeller System Hazard Ratios Propeller System !L3 !L4 ¡L5 Total Events | Events HR ¡ Events HR ; Events HR CAAM 1(1982-1991)- Propeller Separation 2 Gearbox Separation‡ Loss of Control‡ 1 Prop. Sys & Crew Error 5 Crew Error Other· * * 1 * CAAM 2(1992-2000) Propeller Separation 84 17 0.226 0.024 0.012 Autofeather/Pitch Lock 75 1 0.013 PSM+ICR 5 1 * Crew Error * 2 * 2 * 1 * CAAM 3 (2001-2012) Propeller Separation 0.22 Autofeather/Pitch Lock 104 4 0.04 * PSMRR 4 5 * 3 Crew Error * 2 * 1 * 2 Combined t Propeller Separation 93 19 0.226 0.022 1 0.011 Autofeather/Pitch Lock 179 5 0.028 0.000 0.000 PSMRR *0 9 11 3 Crew Error *0 4 * 6 * 3 * † The data is combined here for convenience. The user should review the event descriptions and definitions in the CAAM reports for relevance to the particular issue being assessed.
‡ Data for these categories was only collected in CAAM 1 and not included in the Combined totals.
° Hazard ratios not calculated due to under-reporting of base events.
D-9
AC 39-8A Appendix D D.15 Failure Condition: APU System Event.
• Uncontained. An uncontained rotating component malfunction that allows debris to exit through the APU containment casings.
• Axial uncontained. Major rotating components that exit the APU containment casings in an axial direction (i.e., without penetrating the case).
• Overspeed. Acceleration of a rotor beyond the speed sanctioned in the Type Certificate Data Sheet.
• Fire. Combustion external to the APU casings. Tailpipe fire data and hot air leaks resulting in fire warnings, without combustion, are excluded from the definition and documented separately.
• Tailpipe fire. Fires within the tailpipe and exiting the tailpipe, where flames are visible. Hot starts resulting in a “glow” are excluded.
• Compartment overheat. High-temperature air leaks due to casing highpressure/temperature air duct system malfunctions within the APU.
D-10
AC 39-8A Appendix D Table D-20 - APU Data APU IL3 ¡L4 ¡ L5 Total Events | Events HR | Events HR • Events HR CAAM 1 (1982-1991...
Uncontained 21 Fire 47 7 Crew Error‡ 1 Maintenance‡ 1 Other‡ CAAM 2 (1992-2000) Uncontained 47 Axial Uncontained‡ 15 * Overspeed‡ 63 Fire 45 6 0.133 Tailpipe Fire‡ 28 0.036 Compartment Overheat‡ 242 CAAM 3 (2001-2012) NA° Combined t Uncontained 68 Fire' 92 13 * † The data is combined here for convenience. The user should review the event descriptions and definitions in the CAAM reports for relevance to the particular issue being assessed ‡ Data was only collected in either CAAM 1 report or CAAM 2 report, not both. Not included in "Combined."
° No APU data was collected in CAAM 3 report.
i Hazard ratios not calculated due to likely under-reporting of base events.
D-11
AC 39-8A Appendix D D.16 Failure Condition: Propulsion System malfunction Recognition and Response (PSMRR).
PSMRR is defined as a safety-significant event initiating from a single propulsion system malfunction, excluding the propeller system, which, by itself, does not hazard the airplane, but is compounded by an inappropriate crew response. For example, the crew did not execute their checklist during normal flying duties. A typical example of PSMRR is an IFSD followed by inappropriate crew response that caused the airplane to crash. Not counted are cases of gross error negligence, such as deciding to take off with an engine known to be inoperative. See the AIA and AECMA Project Report on Propulsion System Malfunction plus Inappropriate Crew Response (PSM+ICR), dated November 1998, for additional examples. Note that this condition has previously been referred to as PSM+ICR.
Table D-21 - Propulsion System Malfunction Recognition and Response Data † The data is combined here for convenience. The user should review the event descriptions and definitions in the CAAM reports for relevance to the particular issue being assessed.
‡ Due to the lack of data and likely under-reporting of base events, hazard ratios are not calculated.
D-12
AC 39-8A Appendix D D.17 Failure Condition: Crew Error.
A crew error is defined as a significant safety event caused by a propulsion system malfunction or improper operation that was caused by an inappropriate crew action, excluding sabotage, gross negligence, and suicide. Not included are events where inappropriate crew action causes a propulsion system malfunction through very indirect means such as flying the airplane into the ground or running the airplane into equipment on the taxiway/runway.
Table D-22 - Crew Error Data † The data is combined here for convenience. The user should review the event descriptions and definitions in the CAAM reports for relevance to the particular issue being assessed.
‡ Due to the lack of data and likely under-reporting of base events, hazard ratios are not calculated.
D-13
AC 39-8A Appendix D D.18 Previously Reported Hazards Not Included.
Not all potential hazards that the FAA identified in the prior version of this AC were included for the reasons identified below. You may contact the FAA for additional information on developing hazard ratios in these cases.
D.18.1 The following potential hazards were previously identified and may have resulted in a limited number of multiple HLs 3, 4, or 5 events, but were found to have low hazard ratios or hazard ratios calculated based on significant under-reporting of the base events:
• Contained engine or APU rotor failure;
• Asymmetric thrust – throttle split;
• Asymmetric thrust – single engine reverser non-deployment/no beta on landing;
• Single engine IFSD/power loss;
• Overthrust;
• Engine or APU overspeed;
• Hazardously misleading powerplant or APU indications;
• Loss of inflight restart capability on a critical number of engines;
• Excessive fuel tank differential pressures;
• Flammable fluid leakage – oil/hydraulic; and
• Smoke or toxic products in the cabin.
D.18.2 The following potential hazards were previously identified but either had no data collected, or did not result in any HL 3, 4, or 5 events over the reporting periods:
• Nacelle, pylon, or APU compartment “overheat”;
• Engine or APU exhaust gas impingement;
• Multiple engines small undetected thrust loss; and
• Fuel load imbalance.
D-14