Airworthiness Directive · Amendment 39-21429 · Engine control system wiring
Airbus Helicopters
This airworthiness directive (AD) applies to Airbus Helicopters Model AS350B3 helicopters, certificated in any category, with a Turbomeca ARRIEL 2B engine installed.
The FAA is adopting a new airworthiness directive (AD) for Airbus Helicopters Model AS350B3 helicopters. This AD requires modifying the electrical system of the throttle twist grip, inspecting the routing of a microswitch electrical harness, and correcting the electrical harness routing if it is incorrect. This AD was prompted by reports of the engine remaining in idle when the twist grip was turned from the "forced idle" position to the "flight" position. The actions of this AD are intended to address an unsafe condition on these products.
You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time.
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.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
