1AD/BELL 222/5 - Ng Operating Speed Restrictions

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Bell Helicopter Textron Canada (BHTC) 222 Series Helicopters

AD/BELL 222/5 Ng Operating Speed Restrictions 11/85

Applicability: Bell 222U helicopters with Lycoming LTS101-750C-1 engines installed which have not been modified in accordance with LYC SB 101C-72-00-0079.

Requirement: Install engine operating speed restriction placard/ decal P/N 222-075-221-101 or similar, which reads:

AVOID CONT OPS 86% to 90% Ng

beneath gas producer speed indicators in accordance with Bell Helicopter Textron Alert Service Bulletin No. 222U-85-6.

Note: Temporary Revision No. 85-1 to Model 222U Flight Manual BHT-222U-FM-1 is required whilst this restriction is effective.

Effective: Forthwith.

Background: A number of contained turbine blade failures have occurred due to fatigue caused by vibration stresses when engines are operated in the 86% to 90% speed range. This Directive is issued restricting operation in this range until gas producer turbine wheels are modified in accordance with LYC SB 101C-72-00-0079.