Airworthiness Directive · Amendment 39-19748 · Sikorsky Aircraft Corporation Helicopters
Sikorsky Aircraft Corporation Helicopters
This AD applies to Sikorsky Aircraft Corporation Model S-76C helicopters, certificated in any category, with a Turbomeca, S.A., Arriel 2S1 or Arriel 2S2 engine with an engine collective position transducer (CPT) part number (P/N) 76900-01821-104 or 76900-01821-105 installed.
The FAA is superseding Airworthiness Directive (AD) 2018-10-07 for Sikorsky Aircraft Corporation (Sikorsky) Model S-76C helicopters. AD 2018-10-07 required inspecting the engine collective position transducer (CPT). This new AD retains the requirements of AD 2018-10-07 and expands the applicability. This AD is prompted by the determination that an additional part-numbered engine CPT is affected by the same unsafe condition. The FAA is issuing this AD to address the unsafe condition on these products.
(1) Within 130 hours time-in-service (TIS):
(i) Measure resistance of each engine CPT and replace the CPT if the measured resistance is not within tolerance by following the Accomplishment Instructions, paragraphs 3.C.(1) through 3.C.(8)(b), of Sikorsky S-76 Helicopter Alert Service Bulletin ASB 76-73-8, Revision A, dated December 4, 2015 (ASB 76-73-8A), if using Test Box P/N 76700-40009-042 or by following paragraph 3.B.(11) of Sikorsky Maintenance Manual, SA 4047-76C-2, Temporary Revision No. 73-08, dated September 20, 2017 (TR 73-08) or paragraph 3.B.(11) of Sikorsky Maintenance Manual, SA 4047-76C-2, Temporary Revision No. 73-10, dated June 25, 2019 (TR 73-10), if using Test Box P/N 76700-40009-043. You are not required to use Sikorsky's CPT data sheet or submit a data sheet to Sikorsky.
(ii) Measure the linearity resistance movement of each engine CPT and replace the CPT if there is a linear abnormality or change in resistance that is not within tolerance by following the Accomplishment Instructions, paragraphs 3.D.(1) through 3.D.(14)(b), of ASB 76-73-8A, if using Test Box P/N 76700-40009-042 or by following paragraph 3.B.(12) of TR 73-08 or paragraph 3.B.(12) of TR 73-10, if using Test Box P/N 76700-40009-043. You are not required to use Sikorsky's CPT data sheet or submit a data sheet to Sikorsky.
(iii) Measure the differential voltage of each engine CPT and replace the CPT if the measured voltage is not within tolerance by following the Accomplishment Instructions, paragraphs 3.E. through 3.G.(1) of ASB 76-73-8A, if using Test Box P/N 76700-40009-042 or by following paragraph 3.B.(13) of TR 73-08 or paragraph 3.B.(13) of TR 73-10, if using Test Box P/N 76700-40009-043. You are not required to use Sikorsky's CPT data sheet or submit a data sheet to Sikorsky.
(2) Thereafter, at intervals not to exceed 300 hours TIS:
(i) If using Test Box P/N 76700-40009-042:
(A) Measure resistance of each engine CPT and replace the CPT if the resistance is not within tolerance by following paragraph 4.B.(11) of Sikorsky Maintenance Manual, SA 4047-76C-2, Temporary Revision No. 73-07, dated August 17, 2016 (TR 73-07), except you are not required to use Sikorsky's CPT data sheet or return a failed CPT to Sikorsky.
(B) Measure the linearity resistance movement of each engine CPT and replace the CPT if the movement exceeds tolerance by following paragraphs 4.B.(12)(a) through 4.B.(13)(f) of TR 73-07, except you are not required to use Sikorsky's CPT data sheet or return a failed CPT to Sikorsky.
(C) Measure the differential voltage of each CPT by following paragraphs 4.B.(14) through 4.B.(15)(h) of TR 73-07, except you are not required to use Sikorsky's CPT data sheet. If the maximum voltage is greater than 100 millivolts or the minimum voltage is less than −100 millivolts, replace the CPT.
(ii) For helicopters using Test Box P/N 76700-40009-043:
(A) Measure resistance of each engine CPT and replace the CPT if the resistance is not within tolerance by following paragraph 5.B.(11) of TR 73-07, paragraph 3.B.(11) of TR 73-08, or paragraph 3.B.(11) of TR 73-10, except you are not required to use Sikorsky's CPT data sheet or return a failed CPT to Sikorsky.
(B) Measure the resistance linearity of each engine CPT and replace the CPT if the resistance is not within tolerance by following paragraph 5.B.(12) of TR 73-07, paragraph 3.B.(12) of TR 73-08, or paragraph 3.B.(12) of TR 73-10, except you are not required to use Sikorsky's CPT data sheet or return a failed CPT to Sikorsky.
(C) Measure the differential voltage of each engine CPT and replace the CPT if the resistance is not within tolerance by following paragraphs 5.B.(13)(a) through 5.B.(13)(k) of TR 73-07, paragraph 3.B.(13) of TR 73-08, or paragraph 3.B.(13) of TR 73-10, except you are not required to use Sikorsky's CPT data sheet or return a failed CPT to Sikorsky.
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.
