AD Focuses On Main Rotor Fixing Bolts

The FAA has released an Emergency Airworthiness Directive (AD) (2010-02-51) prompted by a mandatory continuing airworthiness information (MCAI) AD issued by the European Aviation Safety Agency (EASA), the Technical Agent for the Member States of the European Community.

The MCAI states that 2 of the 3 installed main rotor scissor fitting assembly fixing bolts (fixing bolts) on a Model A109K2 helicopter had cracked in flight. Investigation by the manufacturer revealed that the crack was caused by inadequate instructions for installing the bolts. Improper  installation of the main rotor scissor fitting assembly, if not detected and corrected, could result in a crack in a fixing bolt, failure of the fixing bolt, and subsequent loss of control of the helicopter.

The FAA has reviewed Agusta Alert Bollettino Tecnico (ABT) No. 109K-53 for Model A109K2 helicopters and ABT No. 109-131 for Model A109A, A109A II, and A109C helicopters, both dated December 18, 2009. The ABTs specify a one-time inspection to verify the correct installation of the main rotor scissor fitting assembly, part number (P/N) 109-0110-67 or P/N 109-0101-58, to determine if 2 washers are installed under the head of each fixing bolt. If 2 washers are not installed under the head of each fixing bolt, the ABTs specify replacing each fixing bolt with an airworthy fixing bolt, P/N 109-0101-78-5, and installing 2 washers under the head of each fixing bolt.

EASA has issued AD No. 2009-0274-E, dated December 18, 2009, to correct an unsafe condition for the specified Agusta model helicopters. EASA advises that failure of a fixing bolt could lead to loss of control of the helicopter.

These helicopter models have been approved by the aviation authority of Italy and are approved for operation in the United States. Pursuant to our bilateral agreement with Italy, EASA, their technical agent, has notified us of the unsafe condition described in the MCAI AD. We are issuing this AD because we evaluated all information provided by EASA and determined the unsafe condition exists and is likely to exist or develop on other  helicopters of these same type designs. Therefore, this AD requires, within 5 hours time-in-service (TIS), inspecting the main rotor scissor fitting assembly to determine if there are 2 washers installed under the head of each fixing bolt. If there are 2 washers installed under the head of each  fixing bolt, no further action is required.

If there are not 2 washers installed under the head of each fixing bolt, this AD requires, within 25 hours TIS after complying with paragraph (a) of this AD, replacing each fixing bolt and installing 2 washers under the head of each fixing bolt.

This AD differs from the MCAI AD in that we refer to “flight hours” as “hours TIS”. Also, the FAA does not allow an optional date for replacing the fixing bolts.

FMI: www.faa.gov