EASA AD US-2018-10-07: Superseded by FAA AD 2019-19-12

What to do

Operators of Sikorsky S-76C helicopters with the specified CPT must perform initial and recurring CPT inspections as detailed in the AD, using approved test boxes. If inspection results indicate wear, the CPT must be replaced promptly. The AD became effective on June 25, 2018, and compliance with inspection requirements must begin by that date.

Summary

FAA Airworthiness Directive 2018-10-07 is a final rule addressing Sikorsky Aircraft Corporation Model S-76C helicopters equipped with Turbomeca Arriel 2S1 or 2S2 engines having engine collective position transducer (CPT) part number 76900-01821-104 installed. This directive requires inspections of the CPT to detect wear that has caused several momentary One Engine Inoperative (OEI) incidents. The AD aims to prevent unsafe conditions related to CPT wear that could lead to emergency landings.

What changed

This new AD introduces mandatory initial and recurring inspections of the engine CPT by measuring resistance, linearity resistance movement, and differential voltage, with replacement required if wear is detected. It clarifies that momentary OEI conditions are expected rather than full engine failures and allows the use of two different CPT test boxes for inspections. The AD also defers inclusion of CPT part number 76900-01821-105 to a future rulemaking.

Why it matters

This AD is critical for operators and maintenance personnel to identify and address CPT wear before it causes momentary engine power loss, enhancing flight safety. Compliance ensures that helicopters avoid unexpected OEI events that could lead to emergency landings or rejected takeoffs. It also provides clear inspection procedures and test equipment options, facilitating consistent maintenance practices.

What to do

Summary

What changed

Why it matters

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