# Proposed AD FAA-2014-0335: Sikorsky Aircraft Corporation (Sikorsky) Helicopters

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2015-26-10
- Products: Sikorsky
- Product type: Aircraft
- Action: Notice of proposed rulemaking (NPRM).
- Published: June 2, 2014, 79 FR 31231
- Comments due: August 1, 2014
- Became: [AD 2015-26-10](https://openairdocs.org/ad/2015-26-10)
- Docket: FAA-2014-0335 (https://www.regulations.gov/docket/FAA-2014-0335, where comments are filed)
- Project: 2013-SW-021-AD
- FR document: 2014-12738
- Official PDF: https://openairdocs.org/files/sha256/8c/40/8c40d7a8075aac48f7f142bf5b38e1aa1ef3cbc275810d0f506250333c613ad5 (from https://www.govinfo.gov/content/pkg/FR-2014-06-02/pdf/2014-12738.pdf)
- Federal Register: https://www.federalregister.gov/documents/2014/06/02/2014-12738/airworthiness-directives-sikorsky-aircraft-corporation-sikorsky-helicopters
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/949A98774BA7241886257CEB0044E003.0001
- Page: https://openairdocs.org/proposed/FAA-2014-0335

## Summary

We propose to adopt a new airworthiness directive (AD) for Sikorsky Model S-76A, S-76B, and S-76C helicopters with a main gearbox (MGB) installed that has undergone certain repairs. This proposed AD would require inspecting the MGB lower housing jet bores for leaks, paint or caulk blistering, and liner protrusion. This proposed AD is prompted by several reports of MGB low oil pressure warnings which were determined to be the result of unsecured jet bore liners that had protruded. The proposed actions are intended to prevent failure of the MGB from loss of oil, which could result in subsequent loss of control of the helicopter.

## Notices in this docket

- Jun 2, 2014: Notice of proposed rulemaking (NPRM). (first notice), FR document 2014-12738, comments due Aug 1, 2014 (https://www.federalregister.gov/documents/2014/06/02/2014-12738/airworthiness-directives-sikorsky-aircraft-corporation-sikorsky-helicopters)

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