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 Effect of the Failure on Classification Supporting Verification Function ATA Condition Operation the Aircraft, Crew and of the FC (assumptions) Material Method Description Occupants 6310 Engine/ Transmission Coupling Provide torque Loss of TO Aircrew workload Analysis and and rotational engine to increases substantially Test speed to the transmission such that tasks cannot be rotor shaft (coupling) completed accurately.
drive (single Aircrew must conduct engine). an autorotation.
Loss of TO Aircrew workload Analysis and engine to substantially increases to Test transmission handle an OEI (coupling) condition.
drive (dual engine).
Loss of TO Continued safe flight is Analysis and engine not guaranteed due to Test coupling seizure of free wheeling and loss of clutch results in loss of input MR rpm. Leads to module free- uncontrolled flight (no wheeling auto-rotation clutch capability.).
(single & dual engine).
6320 Main Rotor Gearbox Figure AC 27 MG 21-1. Generic Examples by ATA.
Page MG 21 - 33
AC 27-1B, 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 Failure Phase of Effect of the Failure on Classification Notes Supporting Verification ATA Function Description (FC) Condition Operation Occupants the Aircraft, Crew and of the FC (assumptions) Material Method Provide torque Loss of Cruise Aircrew workload Analysis and and rotational lubrication increases substantially Test speed to the to main due to the need to rotor shaft. transmission conduct a landing as soon as possible.
6321 Main Rotor Brake Provide Inadvertent ALL Continued safe flight is Analysis and braking to the activation of not guaranteed. For Test rotor rotor instance, engagement of braking the braking pad during system high power to the main during rotor could create a fire.
flight.
6340 Rotor Drive Indicating System Provide MGB Failure of ALL Continued safe flight Analysis and chip detection chip and landing is not Test detector guaranteed due to the system to degradation of gears detect and below the required load annunciate capability.
the existence of chips.
Figure AC 27 MG 21-1. Generic Examples by ATA.
Page MG 21 - 34
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 Failure Condition Phase of Operation the Aircraft, Crew and Effect of the Failure on of the FC Classification Notes (assumptions) Supporting Material Method Verification Description (FC) Occupants Provide MGB Loss of oil ALL A significant reduction Analysis and oil pressure pressure in safety margins would Test indication indication. exist due to the possible delay in crew action to an actual loss of oil.
Aircrew workload increases slightly due to changing the planned flight and the monitoring of secondary indications.
Erroneous ALL A substantial reduction Analysis and annuncia- in safety margins would Test tion of low exist due to the delayed oil pressure reaction of the crew to warning. an actual loss of oil.
Slight increase in aircrew workload due to conflicting low oil pressure warning and oil pressure indicator.
Figure AC 27 MG 21-1. Generic Examples by ATA.
Page MG 21 - 35
AC 27-1B, 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 Failure Phase of Effect of the Failure on Classification Notes Supporting Verification ATA Function Condition Operation the Aircraft, Crew and of the FC (assumptions) Material Method Description (FC) Occupants Loss of oil ALL Large reduction in the Analysis and pressure aircraft safety margin; Test indication cannot determine if and low oil adequate oil pressure is pressure present. Secondary cues warning. 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 ALL Significant reduction in Analysis and oil 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.
Figure AC 27 MG 21-1. Generic Examples by ATA.
Page MG 21 - 36
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 Failure Phase of Effect of the Failure on Classification Notes Supporting Verification ATA Function Condition Operation the Aircraft, Crew and of the FC (assumptions) Material Method Description (FC) Occupants Misleading ALL Continued safe flight is Analysis oil pressure not guaranteed due to indication loss of all indications of and loss of MGB oil pressure loss low oil and ensuing gearbox pressure seizure.
warning.
Provide Nr Loss of ALL Slight increase in Analysis indication rotor RPM aircrew workload due to and/or Test (Nr) the need to monitor indication. secondary engine instruments.
Figure AC 27 MG 21-1. Generic Examples by ATA.
Page MG 21 - 37
AC 27-1B, 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 Failure Phase of Effect of the Failure Classification Notes Supporting Verification ATA Function Description (FC) Condition Operation on the Aircraft, Crew and Occupants of the FC (assumptions) Material Method 7331 Fuel Flow Loss of fuel ALL The reduction in safety Analysis Indicating flow. margins and functional capability in the system may prohibit continued safe flight and landing.
Malfunction ALL The failure can delay Analysis and loss of crew action long fuel flow enough to prevent indication. continued safe flight and landing.
Misleading ALL A large reduction in Analysis fuel flow safety margins or alert failed. functional capabilities.
7332 Fuel Pressure Loss of fuel ALL The reduction in safety Analysis Indicating pressure. margins and functional capability in the system may prohibit continued safe flight and landing.
Malfunction ALL A combination of a Analysis and loss of malfunction with a loss and Test fuel of indication in the pressure system can delay crew indication. action long enough causing a large reduction in safety margins or functional capabilities.
Figure AC 27 MG 21-1. Generic Examples by ATA.
Page MG 21 - 38
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 Failure Phase of Effect of the Failure Classification Notes Supporting Verification Function ATA Description (FC) Condition Operation on the Aircraft, Crew and Occupants of the FC (assumptions) Material Method Misleading ALL If the indication to the Analysis fuel pilot is a warning, the pressure likely requirement is to indication. land immediately.
Worst case is ditching in poor conditions causing a large reduction in safety margins or functional capabilities.
Figure AC 27 MG 21-1. Generic Examples by ATA.
Page MG 21 - 39
AC 27-1B, 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 75-00-00 - AIR Failure Phase of Effect of the Failure Classification Notes Supporting Verification ATA Function Description (FC) Condition Operation and Occupants on the Aircraft, Crew of the FC (assumptions) Material Method 7510 Engine Anti- Loss of a Cruise A significant loss of Analysis and Icing (A/I) single safety margin due to Test System engine A/I loss of a critical system on a redundant system.
multi-engine aircraft. Significant increase in pilot workload Loss of Cruise Results in a large Analysis and engine A/I reduction in aircraft Test system on a safety margin and a single large increase in pilot engine workload.
aircraft.
7532 Compressor Malfunction Cruise May cause an engine Analysis and Bleed Valve - valve is stall or surge that leads Test failed OPEN loss of one engine.
on one Significant increase in engine of a pilot workload.
multi-engine aircraft.
Malfunction Cruise May cause an engine Analysis and
- valve is stall or surge that leads Test failed OPEN loss of the engine.
on one More than a significant engine on a increase in pilot single workload as the crew engine will likely have to land aircraft. as soon as possible.
Figure AC 27 MG 21-1. Generic Examples by ATA.
Page MG 21 - 40
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 75-00-00 - AIR Failure Phase of Effect of the Failure Classification Notes Supporting Verification ATA Function Description (FC) Condition Operation and Occupants on the Aircraft, Crew of the FC (assumptions) Material Method 7540 Bleed Air Loss of ALL A slight reduction in Analysis and Indicating bleed air safety margins. Test System indication.
A slight increase in pilot workload.
Misleading ALL Misleading indication Analysis and bleed air may cause an Test indication. inappropriate engine setting resulting in a significant reduction in system safety margins.
Figure AC 27 MG 21-1. Generic Examples by ATA.
Page MG 21 - 41
AC 27-1B, 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 Failure Phase of Effect of the Failure Classification Notes Supporting Verification ATA Function Description (FC) Condition Operation on the Aircraft, Crew and Occupants of the FC (assumptions) Material Method 7931 Engine Oil Loss of oil ALL Loss of indication can Analysis Pressure press delay crew action long indication. enough to prevent continued safe flight and landing.
Misleading ALL If the indication to the Analysis and oil press pilot is a warning, the Test indication. likely requirement is to land immediately.
Worst case is ditching in poor conditions causing a large reduction in safety margins or functional capabilities.
7932 Engine Oil Loss of oil ALL Loss of indication is Analysis Quantity quantity considered to be a indication. significant increase to pilot workload but only when required to be displayed per 14 CFR
27.1337(d)(2).
Figure AC 27 MG 21-1. Generic Examples by ATA.
Page MG 21 - 42
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 Failure Phase of Effect of the Failure Classification Notes Supporting Verification ATA Function Description (FC) Condition Operation and Occupants on the Aircraft, Crew of the FC (assumptions) Material Method Misleading ALL If the indication to the Analysis and oil quantity pilot is a warning, the Test indication. likely pilot action is to land immediately.
Worst case is ditching in poor conditions causing a large reduction in safety margins or functional capabilities.
7933 Engine Oil Loss of oil ALL Loss of indication in Analysis and Temperature temperature the system can delay Test indication. crew action long enough to cause a large reduction in safety margins or functional capabilities.
Misleading ALL If the indication to the Analysis and oil pilot is a warning, the Test temperature likely requirement is to indication. land immediately.
Worst case is ditching in poor conditions causing a large reduction in safety margins or functional capabilities.
Figure AC 27 MG 21-1. Generic Examples by ATA.
Page MG 21 - 43
CHAPTER 3
AIRWORTHINESS STANDARDS
NORMAL CATEGORY ROTORCRAFT
MISCELLANEOUS GUIDANCE (MG) AC 27 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.
falo Species 0n,s) pa 21, co, SEnding European Requirements
(2) ACs 27-1B and 29-2C.
c. Background. Different types of OE 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 OE conditions for training purposes without using the engine and drive system OE 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. OE 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 certification process should begin with a clear declaration of the objective of the OE 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