AD 2021-04-08 Airworthiness Directives; Airbus Helicopters

This AD becomes effective April 1, 2021.

Special flight permits are prohibited.

(1) The Manager, Strategic Policy Rotorcraft Section, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the Strategic Policy Rotorcraft Section, send it to: Manager, Strategic Policy Rotorcraft Section, FAA, 10101 Hillwood Pkwy., Fort Worth, TX 76177; telephone 817-222-5110; email 9-ASW-FTW-AMOC-Requests@faa.gov. (2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office.

Before the next practice autorotation, before the next simulated governor failure, or within 330 hours time-in-service, whichever occurs first, modify the electrical operation of the throttle twist grip to give priority to the HydroMechanical Unit flight position when the microswitch does not operate correctly at forced idle (corresponds to Airbus Helicopters Modification (MOD) 073357) as follows: (1) For helicopters without MOD 073087 and without MOD 073135 installed: (i) Install box “69K” on the Full Authority Digital Engine Control plate, relay “81K” on frame X1310, install fuses on the console end comprising circuit-breaker panels “31 ALPHA” and “32 ALPHA,” and modify the electrical wiring by following the Accomplishment Instructions, paragraph 3.B.2.a. of Airbus Helicopters Alert Service Bulletin No. AS350-67.00.43, Revision 3, dated June 16, 2016 (ASB AS350-67.00.43), except you are not required to discard parts. (ii) Inspect the routing of microswitch electrical harness “53K” for correct installation by following paragraph 3.B.2.e. of ASB AS350-67.00.43. If the wiring routing is incorrect, before further flight, correct the wiring routing by following paragraph 3.B.2.f. of ASB AS350-67.00.43. (2) For helicopters with MOD 073087 (series) and without MOD 073135 installed: (i) Install relays “54K” and “81K” on frame X1310 and modify the electrical wiring by following paragraph 3.B.2.b. of ASB AS350-67.00.43. (ii) Inspect the routing of microswitch electrical harness “53K” for correct installation by following paragraph 3.B.2.e. of ASB AS350-67.00.43. If the wiring routing is incorrect, before further flight, correct the wiring routing by following paragraph 3.B.2.f. of ASB AS350-67.00.43. (3) For helicopters with MOD 073087 (retrofit) and without MOD 073135 installed: (i) Install relay “81K” on frame X1310 and modify the electrical wiring by following paragraph 3.B.2.c. of ASB AS350-67.00.43. (ii) Inspect the routing of microswitch electrical harness “53K” for correct installation by following paragraph 3.B.2.e. of ASB AS350-67.00.43. If the wiring routing is incorrect, before further flight, correct the wiring routing by following paragraph 3.B.2.f. of ASB AS350-67.00.43. (4) For helicopters with MOD 073087 and with MOD 073135 installed: (i) Install relay “81K” on frame X1310 and modify the electrical wiring by following paragraph 3.B.2.d. of ASB AS350-67.00.43. (ii) Inspect the routing of microswitch electrical harness “53K” for correct installation by following paragraph 3.B.2.e. of ASB AS350-67.00.43. If the wiring routing is incorrect, before further flight, correct the wiring routing by following paragraph 3.B.2.f. of ASB AS350-67.00.43. (5) For helicopters with MOD 073084 and with MOD 073222 installed: (i) Install relay “81K” on frame X1310 and modify the electrical wiring by following paragraph 3.B.2.g. of ASB AS350-67.00.43, except you are not required to scrap parts. (ii) Inspect the routing of microswitch electrical harness “53K” for correct installation by following paragraph 3.B.2.e. of ASB AS350-67.00.43. If the wiring routing is incorrect, before further flight, correct the wiring routing by following paragraph 3.B.2.f. of ASB AS350-67.00.43. (6) For helicopters with optional Autopilot “81K” and without MOD 073222 installed: (i) Position relay “81K” on frame X1310 by following paragraph 3.B.2.h. of ASB AS350-67.00.43. (ii) Inspect the routing of microswitch electrical harness “53K” for correct installation by following ASB AS350- 67.00.43, paragraph 3.B.2.e. If the wiring routing is incorrect, before further flight, correct the wiring routing by following paragraph 3.B.2.f. of ASB AS350-67.00.43.

This AD defines the unsafe condition as failure of the electrical operation of the throttle twist grip, which can prevent switching from “IDLE” mode to “FLIGHT” mode. During autorotation training or during governor failure training (when the throttle grip is turned in the low flow direction), this condition prohibits recovery from a practice autorotation and compels the pilot to continue the autorotation to the ground. This condition could result in unintended touchdown to the ground at a flight-idle power setting, damage to the helicopter, and injury to occupants.