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.
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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 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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(iii) Limited to essential crew only.
(iv) Detailed description of the safety features implemented in the system and their use during normal and emergency conditions.
(v) Weight limitations for training, which should be presented in the same format used for the category A Weight-Ambient-Temperature Charts.
(vi) Normal and emergency procedures to be applied; these procedures need to include those necessary to exit the training in case of emergency.
(vii) Performance information (i.e., rate of climb, take off and landing distances), if different from non-training). Performance information in case of actual engine failure while in training mode is not required.
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AC 29-2 C, Chg 4 5/1/2014
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CHAPTER 3
AIRWORTHINESS STANDARDS
TRANSPORT CATEGORY ROTORCRAFT
MISCELLANEOUS GUIDANCE (MG) AC 29 MG 23 AUTOMATIC FLIGHT GUIDANCE AND CONTROL SYSTEMS (AFGCS) INSTALLATION IN PART 29 ROTORCRAFT.
a. Purpose.
(1) This guidance recognizes the following Radio Technical Commission for Aeronautics (RTCA) documents as acceptable for showing compliance with regulatory requirements for the installation of automatic flight control guidance and control systems (AFGCS).
(i) RTCA Document DO-325, Minimum Operational Performance Standards (MOPS) for Automatic Flight Guidance and Control Systems and Equipment, issued December 8, 2010.
(ii) RTCA Document DO-336, Guidance for Certification of Installed Automatic Flight Guidance and Control Systems (AFGCS) for Part 27/29 Rotorcraft, issued March 21, 2012.
(2) RTCA Document DO-325 contains the minimum operational performance standards (MOPS) for AFGCS equipment, included by reference in TSO-C198. DO-336 provides guidance on obtaining installation approval of AFGCS in rotorcraft. It invokes parts of D0-325 as performance standards applicable for installation of AFGCS equipment in rotorcraft. It provides guidance on conducting a safety assessment.
Lastly, DO-336 lists the regulations applicable to an AFGCS installation and acceptable methods of compliance to those regulations.
(3) This guidance is not mandatory. It describes an acceptable means, but not the only means, for showing compliance with applicable 14 CFR regulations. Following this guidance alone does not guarantee acceptance by the FAA. D epending on circumstances, we may require additional substantiation or design changes as a basis for finding compliance.
b. Background. Technical standard order (TSO), TSO-C198, Automatic Flight Guidance and Control System (AFGCS) Equipment, replaced TSO-C9c, Automatic Pilots, and TSO-C52b, Flight Director Equipment. TSO -C198 identifies a new comprehensive minimum operation performance standard (MOPS) under RTCA Document DO-325 and qualifications for software and airborne electronic hardware.
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AC 29-2C, Chg 6 7/25/2014
Not e: The i ntent was to highlight to the system designer that early coordination with an aircraft original equipment manufacturer (OEM) is important to minimize the compliance requirements at the time of installation, and that even without an OEM, the guidance is relevant when installing the system.
c. Guidance for the use of RTCA Documents DO-325 and DO-336.
(1) RTCA Document DO-325 identifies the typical functions of an AFGCS. We recommend that AFGCS equipment manufacturers obtain technical standard order authorization (TSOA) for TSO-C198 to minimize compliance showings that would be required at installation approval stage. There should be a declaration of any non-TSO functions in the TSOA application so there can be an appropriate evaluation and acceptance of the software and hardware qualification data related to those functions. If AFGCS equipment does not have TSOA for TSO-C198, the applicant for installation approval would have to show compliance with the DO-325 MOPS, as appropriate to functions provided, and conduct the necessary software and hardware qualifications defined in DO-178 and DO-254 guidance documents.
(2) RTCA Document DO-336 has two primary focus items: to highlight the requirements for a proper safety assessment (Chapter 8) and the compliance demonstration (Chapter 9). Each of these should be discussed with the appropriate Aircraft Certification Office (ACO) very early in the program and included in the certification plan.
d. References.
(1) 14 CF R Regulations (available at http://rgl.faa.gov/):
Section Title
29.671 General. (Control Systems)
29.672 Stability augmentation, automatic, and power-operated systems.
29.1309 Equipment, systems, and installations.
29.1329 Automatic pilot system.
29.1335 Flight director systems.
Appendix B to Part 29 Airworthiness Criteria for Helicopter Instrument flight
(2) TSOs (available at http://rgl.faa.gov/):
TSO Title TSO-C198 Automatic Flight Guidance and Control system (AFGCS) Equipment Page MG 23 - 2
(3) ACs (refer to current version; available at http://rgl.faa.gov/):
AC Title 20-115 Radio Technical Commission for Aeronautic, Inc., Document RTCA/DO-178B 20-138 Airworthiness Approval of Positioning and Navigation Systems 20-152 RTCA, Inc., Document RTCA/DO-254, Design Assurance Guidance for Airborne Electronic Hardware.
21-50 Installation of TSOA Articles and LODA Appliances 29-2, Section
29.671 Control Systems - General.
29-2, Section
29.672 Stability Augmentation, Automatic, and Power-Operated Systems.
29-2, Section
29.1309 Equipment, Systems, and Installations.
29-2, Section
29.1329 Automatic Pilot System.
29-2, Section
29.1335 Flight Director Systems.
(4) Industry standards (refer to the current version; RTCA documents are available at www.rtca.org and SAE international documents are available at www.sae.org):
Document Title RTCA/ DO-178 Software Considerations in Airborne Systems and Equipment Certification RTCA/ DO-254 Design Assurance Guidance for Airborne Electronic Hardware RTCA/ DO-325 Minimum Operational Performance Standards (MOPS) for Automatic Flight Guidance and Control Systems and Equipment, issued December 8, 2010.
RTCA/ DO-336 Guidance for Certification of Installed Automatic Flight Guidance and Control Systems (AFGCS) for Part 27/29 Rotorcraft, issued March 21, 2012.
SAE, International ARP 4754 Guidelines for Development of Civil Aircraft and Systems SAE, International ARP 4761 Guidelines and Methods for Conducting the Safety Assessment Process on Civil Airborne Systems and Equipment Page MG 23 - 3
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