# Proposed AD FAA-2012-0945: Sikorsky Aircraft Corporation (Sikorsky) Model Helicopters

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2013-26-13
- Products: Sikorsky
- Product type: Aircraft
- Action: Supplemental notice of proposed rulemaking (SNPRM); reopening of the comment period.
- Published: July 23, 2013, 78 FR 44052
- Comments due: September 23, 2013
- Became: [AD 2013-26-13](https://openairdocs.org/ad/2013-26-13)
- Docket: FAA-2012-0945 (https://www.regulations.gov/docket/FAA-2012-0945, where comments are filed)
- Project: 2010-SW-110-AD
- FR document: 2013-17627
- Official PDF: https://openairdocs.org/files/sha256/0c/bc/0cbcaa58818ed115629bb3253740a902555f1743519910f2524035307c0cfd11 (from https://www.govinfo.gov/content/pkg/FR-2013-07-23/pdf/2013-17627.pdf)
- Federal Register: https://www.federalregister.gov/documents/2013/07/23/2013-17627/airworthiness-directives-sikorsky-aircraft-corporation-sikorsky-model-helicopters
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/3029668D545C348986257BB1004B5AB3.0001
- Page: https://openairdocs.org/proposed/FAA-2012-0945

## Summary

We are revising an earlier proposed airworthiness directive (AD) for the Sikorsky Model S-70, S-70A, S-70C, S-70C (M), and S-70C (M1) helicopters with General Electric (GE) T700-GE-401C or T700-GE- 701C engines installed, which proposed establishing new fatigue life limits for certain GE engine gas generator turbine (GGT) rotor parts. The proposed AD was prompted by a reevaluation of the method for determining the life limit for certain GE engine gas generator turbine (GGT) rotor parts and the determination that these life limits need to be based on low cycle fatigue (LCF) events instead of hours time-in- service. This action would retain the previously proposed requirements but correct the life limit formula for a certain GGT rotor part. The proposed actions are intended to prevent fatigue failure of a GGT rotor part, engine failure, and subsequent loss of control of the helicopter.

## Notices in this docket

- Sep 7, 2012: Notice of proposed rulemaking (NPRM). (first notice), FR document 2012-22064, comments due Nov 6, 2012 (https://www.federalregister.gov/documents/2012/09/07/2012-22064/airworthiness-directives-sikorsky-aircraft-corporation-sikorsky-model-helicopters)
- Jul 23, 2013: Supplemental notice of proposed rulemaking (SNPRM); reopening of the comment period., FR document 2013-17627, comments due Sep 23, 2013 (https://www.federalregister.gov/documents/2013/07/23/2013-17627/airworthiness-directives-sikorsky-aircraft-corporation-sikorsky-model-helicopters)

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.