ATA 63-00-00 – MAIN ROTOR DRIVE ATA Function Description Failure Condition (FC) Phase of Operation Effect of the Failure on the Aircraft, Crew and Occupants Classification of the FC Notes (assumptions) Supporting Material Verification Method Loss of oil ALL Large reduction in the Analysis and pressure aircraft safety margin; Test indication and cannot determine if low oil adequate oil pressure is pressure present. Secondary warning. cues may be present to pilot (Increase oil temperature, vibration and noise levels, in case of actual loss of MGB oil).
Substantial increase in aircrew workload.
Misleading oil ALL Significant reduction in Analysis and pressure the aircraft safety Test indication. margin due to erroneous oil pressure indication (reads normal but actual oil pressure is low).
Substantial increase in aircrew workload.
Misleading oil ALL Continued safe flight is Analysis pressure not guaranteed due to indication and loss of all indications of loss of low oil MGB oil pressure loss pressure and ensuing gearbox warning. seizure.
Figure AC 29 MG 21-1. Generic Examples by ATA.
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AC 29-2C, Chg 7 2/4/2016 Note: Not all ATA chapters or subchapters have been included. Also, the italicized entries are not usually included in the failure condition description but in the systems description or assumptions section.
ATA 63-00-00 – MAIN ROTOR DRIVE ATA Function Description Failure Condition (FC) Phase of Operation Effect of the Failure on the Aircraft, Crew and Occupants Classification of the FC Notes (assumptions) Supporting Material Verification Method Provide Nr indication Loss of rotor RPM (Nr) indication.
ALL Slight increase in aircrew workload due to the need to monitor secondary engine instruments.
Analysis and/or Test Figure AC 29 MG 21-1. Generic Examples by ATA.
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ATA 73-00-00 - ENGINE FUEL AND CONTROL ATA Function Description Failure Condition (FC) Phase of Operation Effect of the Failure on the Aircraft, Crew and Occupants Classification of the FC Notes (assumptions) Supporting Material Verification Method 7331 Fuel Flow Indicating Loss of fuel flow.
ALL The reduction in safety margins and functional capability in the system may prohibit continued safe flight and landing.
Analysis Malfunction and loss of fuel flow indication.
ALL The failure can delay crew action long enough to prevent continued safe flight and landing.
Analysis Misleading fuel flow alert failed.
ALL A large reduction in safety margins or functional capabilities.
Analysis 7332 Fuel Pressure Indicating Loss of fuel pressure.
ALL The reduction in safety margins and functional capability in the system may prohibit continued safe flight and landing.
Analysis Malfunction and loss of fuel pressure indication.
ALL A combination of a malfunction with a loss of indication in the system can delay crew action long enough causing a large reduction in safety margins or functional capabilities.
Analysis and Test Figure AC 29 MG 21-1. Generic Examples by ATA.
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AC 29-2C, Chg 7 2/4/2016 Note: Not all ATA chapters or subchapters have been included. Also, the italicized entries are not usually included in the failure condition description but in the systems description or assumptions section.
ATA 73-00-00 - ENGINE FUEL AND CONTROL ATA Function Description Failure Condition (FC) Phase of Operation Effect of the Failure on the Aircraft, Crew and Occupants Classification of the FC Notes (assumptions) Supporting Material Verification Method Misleading fuel pressure indication.
ALL If the indication to the pilot is a warning, the likely requirement is to land immediately.
Worst case is ditching in poor conditions causing a large reduction in safety margins or functional capabilities.
Analysis Figure AC 29 MG 21-1. Generic Examples by ATA.
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ATA 75-00-00 - AIR ATA Function Description Failure Condition (FC) Phase of Operation Effect of the Failure on the Aircraft, Crew and Occupants Classification of the FC Notes (assumptions) Supporting Material Verification Method 7510 Engine Anti- Icing (A/I) System Loss of a single engine A/I system on a multi-engine aircraft.
Cruise A significant loss of safety margin due to loss of a critical redundant system.
Significant increase in pilot workload.
Analysis and Test Loss of engine A/I system on a single engine aircraft.
Cruise Results in a large reduction in aircraft safety margin and a large increase in pilot workload.
Analysis and Test 7532 Compressor Bleed Valve Malfunction valve is failed OPEN on one engine of a multi-engine aircraft.
Cruise May cause an engine stall or surge that leads loss of one engine.
Significant increase in pilot workload.
Analysis and Test Malfunction valve is failed OPEN on one engine on a single engine aircraft.
Cruise May cause an engine stall or surge that leads loss of the engine.
More than a significant increase in pilot workload as the crew will likely have to land as soon as possible.
Analysis and Test Figure AC 29 MG 21-1. Generic Examples by ATA.
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AC 29-2C, Chg 7 2/4/2016 Note: Not all ATA chapters or subchapters have been included. Also, the italicized entries are not usually included in the fail ure condition description but in the systems description or assumptions section.
ATA 75-00-00 - AIR ATA Function Description Failure Condition (FC) Phase of Operation Effect of the Failure on the Aircraft, Crew and Occupants Classification of the FC Notes (assumptions) Supporting Material Verification Method 7540 Bleed Air Indicating System Loss of bleed air indication.
ALL A slight reduction in safety margins.
A slight increase in pilot workload.
Analysis and Test Misleading bleed air indication.
ALL Misleading indication may cause an inappropriate engine setting resulting in a significant reduction in system safety margins.
Analysis and Test Figure AC 29 MG 21-1. Generic Examples by ATA.
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ATA 79-00-00 – OIL ATA Function Description Failure Condition (FC) Phase of Operation Effect of the Failure on the Aircraft, Crew and Occupants Classification of the FC Notes (assumptions) Supporting Material Verification Method 7931 Engine Oil Pressure Loss of oil press indication.
ALL Loss of indication can delay crew action long enough to prevent continued safe flight and landing.
Analysis Misleading oil press indication.
ALL If the indication to the pilot is a warning, the likely requirement is to land immediately.
Worst case is ditching in poor conditions causing a large reduction in safety margins or functional capabilities.
Analysis and Test 7932 Engine Oil Quantity Loss of oil quantity indication.
ALL Loss of indication is considered to be a significant increase to pilot workload but only when required to be displayed per 14 CFR
29.1337(d)(2).
Analysis Figure AC 29 MG 21-1. Generic Examples by ATA.
Page MG 21 - 43
AC 29-2C, Chg 7 2/4/2016 Note: Not all ATA chapters or subchapters have been included. Also, the italicized entries are not usually included in the failure condition description but in the systems description or assumptions section.
ATA 79-00-00 – OIL ATA Function Description Failure Condition (FC) Phase of Operation Effect of the Failure on the Aircraft, Crew and Occupants Classification of the FC Notes (assumptions) Supporting Material Verification Method Misleading oil quantity indication.
ALL If the indication to the pilot is a warning, the likely pilot action is to land immediately.
Worst case is ditching in poor conditions causing a large reduction in safety margins or functional capabilities.
Analysis and Test 7933 Engine Oil Temperature Loss of oil temperature indication.
ALL Loss of indication in the system can delay crew action long enough to cause a large reduction in safety margins or functional capabilities.
Analysis and Test Misleading oil temperature indication.
ALL If the indication to the pilot is a warning, the likely requirement is to land immediately.
Worst case is ditching in poor conditions causing a large reduction in safety margins or functional capabilities.
Analysis and Test Figure AC 29 MG 21-1. Generic Examples by ATA.
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CHAPTER 3
AIRWORTHINESS STANDARDS
TRANSPORT CATEGORY ROTORCRAFT
MISCELLANEOUS GUIDANCE (MG) AC 29 MG 22 ROTORCRAFT ONE ENGINE INOPERATIVE (OEI) TRAINING MODE.
a. Purpose. This guidance provides a means to achieve airworthiness approval for OEI training mode to be installed on rotorcraft. These devices have been mainly designed to allow category A training without using the OEI ratings thus eliminating the need of extra maintenance for the engines and drive system. This guidance does not change the regulatory requirements and does not authorize changes in, or deviations from, regulatory requirements. These guidelines are developed for category A rotorcraft. If an applicant would like to develop such a system for category B rotorcraft, additional requirements may be applied by the certification authority.
b. References and Related Documents.
(1) 14 CFR parts 21, 29, 33, and corresponding European Requirements (Certification Specifications) part 21, CS-29, CS-E.
(2) AC 29-2C.
c. Background. Different types of OEI training modes and similar systems have been developed and are likely to be developed in the future. Their intent was to provide operators with a means to simulate OEI conditions for training purposes without using the engine and drive system OEI ratings. This type of installation requires an appropriate level of qualification, commensurate to the criticality of the most severe effects on the rotorcraft.
d. Definitions. OEI Training mode: for the purpose of this guidance material, a system or device designed to train the flightcrew by simulating, with an appropriate weight, the OEI conditions, reducing the power of the engines without accessing the actual OEI engine and drive system ratings. This includes cockpit controls and display indications necessary for the flightcrew to safely operate the system or device.
e. Certification Approach. There are different basic aspects to consider when approaching an OEI Training Mode that should be addressed in the proposed certification plan.
(1) System purpose definition. The cert ification process should begin with a clear declaration of the objective of the OEI training mode. Past experiences have shown that these type of systems have been mainly designed to allow operators to train their flightcrew on category A procedures without cutting one engine to idle through the Page MG 22 - 1
AC 29-2C, Chg 4 5/1/2014
engine controls; however, the purpose could also be extended to simulate an engine failure during other conditions (i.e., failure during the cruise). In any case, the maneuver to be simulated with its initial and final points has to be clearly identified by the applicant in order to prepare the certification plan.
(2) Functional Hazard Assessment.
(i) The purpose of the system is the input for the hazard assessment where all the potential failures are identified and appropriately classified taking into account the most critical phase of flight, thus establishing in a systematic way the integrity levels required for each function provided. It is to be noted that an OEI Training Mode is designed to increase the level of safety relative to traditional training operations and therefore the design of the systems should be such that the associated functional failures are never more severe than those associated to an engine cut intentionally to idle. It should be recognized, however, that operation in training mode is an intentional operation in a degraded condition and that the consequences of certain failures may be more severe than those expected in normal operation.
(ii) The functional hazard assessment has to take into account the other systems that interact with the OEI Training Mode (typically the engine control system and the cockpit displays) and all the potential failures that can occur during operation of the training mode. The effect of engine failures and malfunctions that are likely to occur during the operation of the system need to be taken into account. The functional hazard assessment should also cover the failure associated with the safety devices introduced in the system.
(3) Engine failures. Actual engine fa ilure while in OEI training mode should be addressed. While recognizing that an actual failure during training mode is potentially more severe than one during normal operation, adequate safety devices should be provided to minimize the consequences of actual engine failure during training mode.
(4) Display of powerplant instruments. There may be different ways to present the engine data during the OEI training mode functioning. Past experience has shown that some applicants have developed systems where during the simulation, engine limits and associated cautions and warnings are re-scaled in order to present to the flightcrew the same scenario that would occur in case of an actual engine failure. As the current part 29 requirements (including § 29.1305) do not allow displaying biased parameters, the applicant should show an equivalent level of safety with respect to §§ 29.1305 and 29.1549. In particular, while the training mode is engaged, the pilot being trained should be provided with a set of information related to the training drill and not be confused by other data; the safety pilot or instructor should be informed of any abnormal conditions. If a rotor droop is gen erated during the training maneuver, it is acceptable that the NR indicator shows the limits relevant to OEI conditions even if both engines are running.
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(5) Management of Engine Power.
(i) Careful consideration has to be given to the method implemented by the applicant to simulate the engine failure. As of today, two different methods have been used:
(A) Reducing one engine to flight idle and using the other engine up to a limit chosen by the applicant.
(B) Reducing both engines to an intermediate power and use the total power available to simulate the OEI power.
(ii) The second method is expected to provide better acceleration characteristics in case a failure occurs to one engine during the use of training mode.
However, if an applicant would like to implement the first method, evidence has to be provided that the engine accelerating characteristics are acceptable. In both cases, the OEI training engine acceleration characteristics have to be demonstrated by the applicant for the envelope for which approval of the system is sought.
(6) Human Interface Aspects. The human interface aspects of the system have to be carefully considered and appropriately addressed in the certification plan. The information provided to the flightcrew during normal operation of the system and during emergency situation is the main subject of the investigation in order to assess the effectiveness and avoid misleading information on the status of the system that can result in flightcrew errors. During the assessment, consideration should be given to:
(i) Color coding.
(ii) Labeling of the controls (e.g., switches, buttons, etc.) used by the training mode.
(iii) Clear and unambiguous identification of the status of the system; all the parameters that are presented to the flightcrew in a modified scale have to be clearly identified and easily recognizable by the flightcrew.
(iv) OEI training control segregated from the standard engine controls.
(v) Flightcrew alerts. If flightcr ew alerts are generated by the OEI training system, consideration should be given to the following points:
(A) Prioritization of OEI training alerts with respect to those generated in case of actual failures. The OEI training alerts should not change the priority given to the helicopter systems alerts or introduce a delay when these are generated.
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AC 29-2C, Chg 4 5/1/2014 (B) Capability of the flightcrew to distinguish the OEI training alerts from those generated by the other helicopter systems. Distinguishable alerts will prevent flightcrew confusion of the actual status of the rotorcraft.
(C) Representation of OEI training alerts with respect to the actual case for which the system is designed. Lack of co mplete representation of the OEI training alerts can be accepted and documented in the rotorcraft flight manual (RFM).
(7) Representativeness of the maneuver. Although the final decision on the use of the system for training purposes is the responsibility of the national operational authority, the applicant and certificating authority should ensure that the system adequately represents the actual maneuvers the system is designed to simulate. In this regard, the certification team should:
(i) Ensure that the engine failure dynamics of the training mode favorably compare with an actual engine failure. This can be accomplished by comparing the time histories of Ng/torque during an actual engine failure and a training mode engine failure.
(ii) Qualitatively evaluate the piloting techniques required for the training maneuver and the maneuvers used for certification. Ensure the techniques are sufficiently similar to provide adequate training.
(iii) If the training mode does not adequately replicate portions of an OEI event, to include a realistic reproduction of the resultant flight path, those areas should be identified in the RFM (e.g., “The OEI training mode does not accurately represent second stage climb performance.”).
(8) Limitations and Performance Charts.
(i) RFM data necessary for the use of the system typically include:
(A) Weight limitations for training.
(B) Performances associated to the system operative (e.g., rate of climb, take off and landing distances.
(ii) This data should be validated by actual tests or analysis validated by tests or a combination of both to assure the same level of accuracy as the other RFM data.
(9) RFM. The RFM should contain the following information:
(i) Description of the system and its functions.
(ii) Clear statement on the scope of the training mode and the extent of the validity of the system.
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