Main Rotor Blades May Fail During Flight

The FAA has issued an emergency airworthiness directive (EAD) (2012-02-51) for Bell Helicopter Textron Canada Limited (Bell) Model 206L, 206L-1, 206L-3, and 206L-4 helicopters with certain main rotor blades installed.

Transport Canada Civil Aviation (TCCA), has issued TCCA AD No. CF-2011-44R1, dated February 1, 2012, to correct an unsafe condition for the Bell 206L, L-1, L-3, and L-4 helicopters. TCCA advises that there is no reliable inspection method to detect the cracks on these blades before blade failure and has mandated a reduced life limit on all affected blades, and removal from service for any main rotor blades exceeding the new life limit. This EAD is prompted by two accident investigations which revealed the main rotor blade failed because of fatigue cracking. Bell has determined the fatigue cracks occurred as a result of the use by a Bell supplier of unapproved manufacturing processes, which have since been corrected, and are limited to a specific range of part numbers and serial numbers. These EAD actions are intended to prevent failure of the main rotor blade and subsequent loss of control of the helicopter.

These helicopters have been approved by the aviation authority of Canada and are approved for operation in the United States. Pursuant to the FAAs bilateral agreement with Canada, TCCA has notified the agency of the unsafe condition described in the TCCA AD. The FAA is issuing this EAD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of these same type designs.

Related Service Information
Bell Helicopter Alert Service Bulletin No. 206L-09-159 Revision A, dated November 13, 2009 (ASB 206L-09-159), describes procedures to identify and mark the affected main rotor blades, requires a ”recurring wipe check,” and requires performing a one-time radiographic inspection with the results to be determined by Bell.

EAD Requirements
This EAD requires reducing the life limit from 3,600 hours time-in-service (TIS) to 1,400 hours TIS for certain part numbered and serial numbered main rotor blades, revising the life limit in the Airworthiness Limitations section of the Instructions for Continued Airworthiness or maintenance manual, and recording the revised life limit on the component history card or equivalent record. There are no significant differences between this EAD and the TCCA AD.

Before further flight:

• Reduce the life limit of the main rotor blades with a serial number listed in Table 1 of this EAD from 3,600 hours time-in-service (TIS) to 1,400 hours TIS; revise the life limit in the Airworthiness Limitations section of the Instruction for Continued Airworthiness or maintenance manual; and record the revised life limit on the component history card or equivalent record.
• Remove from service any main rotor blade which has accumulated 1,400 or more hours TIS.

Special flight permits are prohibited.

The Manager, Safety Management Group, FAA, may approve AMOCs for this EAD. Send your proposal to: Sharon Miles, Aerospace Engineer, FAA, Rotorcraft Directorate, Regulations and Policy Group, 2601 Meacham Blvd., Fort Worth, Texas 76137, telephone (817) 222 5110, e-mail sharon.y.miles@faa.gov.

For operations conducted under a Part 119 operating certificate or under Part 91, Subpart K, the FAA suggests that you notify your principal inspector, or lacking a principal inspector, the manager of the local flight standards district office or certificate holding district office, before operating any aircraft complying with this EAD through an AMOC.

FMI: EAD