# Proposed AD FAA-2011-0596: Eurocopter Canada Ltd. Model BO 105 LS A-3 Helicopters

- Type: Proposed airworthiness directive (not in force)
- Status: Comment period closed
- Products: Eurocopter Canada
- Product type: Aircraft
- Action: Notice of proposed rulemaking (NPRM).
- Published: August 23, 2011, 76 FR 52593
- Comments due: October 24, 2011
- Docket: FAA-2011-0596 (https://www.regulations.gov/docket/FAA-2011-0596, where comments are filed)
- Project: 2008-SW-37-AD
- FR document: 2011-21472
- Official PDF: https://openairdocs.org/files/sha256/99/f4/99f4705f6b39a2cf2f54d8651ee6c27c7b16e3b5af288de756c18c449b7fac0a (from https://www.govinfo.gov/content/pkg/FR-2011-08-23/pdf/2011-21472.pdf)
- Federal Register: https://www.federalregister.gov/documents/2011/08/23/2011-21472/airworthiness-directives-eurocopter-canada-ltd-model-bo-105-ls-a-3-helicopters
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/B569157661829F2A862578F50046A567.0001
- Page: https://openairdocs.org/proposed/FAA-2011-0596

## Summary

This document proposes superseding an existing airworthiness directive (AD) for Eurocopter Canada Ltd. Model BO 105 LS A-3 helicopters. That AD currently requires establishing a life limit for certain tension-torsion (TT) straps. This action would require reducing the "number of flights'' life limit and providing a time-in-service (TIS) life limit for those TT straps. This proposal is prompted by a recalculation by the manufacturer and subsequent changes to the service information related to the retirement time of the TT strap initially adopted as a result of an accident in which a main rotor blade (blade) separated from a Eurocopter Deutschland GMBH (ECD) Model MBB-BK 117 helicopter due to fatigue failure of a TT strap. The same part-numbered TT strap is used on Model BO 105 LS A-3 helicopters. The actions specified by the proposed AD are intended to prevent fatigue failure of a TT strap, loss of a blade, and subsequent loss of control of the helicopter.

## Notices in this docket

- Aug 23, 2011: Notice of proposed rulemaking (NPRM). (first notice), FR document 2011-21472, comments due Oct 24, 2011 (https://www.federalregister.gov/documents/2011/08/23/2011-21472/airworthiness-directives-eurocopter-canada-ltd-model-bo-105-ls-a-3-helicopters)

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