The US Federal Aviation Administration (FAA) has issued a notice of proposed rulemaking (NPRM) document for a proposed airworthiness directive regarding Piaggio Aero Industries P180 aircraft. The proposed AD is based off mandatory continuing airworthiness information (MCAI) that originated from EASA AD no. 2012-0066, dated April 24, 2012.

The MCAI requires operators to identify and correct an unsafe condition on the twin-engined turboprop model, which it describes as "jamming of the external bearing of the screwjack drive gear, which resulted in failure of the main wing outboard flap external actuator."

The EASA AD says that P180 operators reported failures of the main wing outboard flap, and an investigation yielded information about the aircraft's external actuator stopping after the screwjack drive gear disengaged from its seat. The inner actuator continued to run. The AD says that the gear disengaging was due to the jamming of the external bearing.

The MCAI says that if this issue is not corrected, it could lead to "an asymmetrical flap actuators operation and cause an interference between the flap and adjacent aileron, possibly resulting in reduced control of the aeroplane."

The EASA AD required operators to install a covering cage on the screw jack as a temporary corrective action, which does not allow the affected gear to disengage. Piaggio has released the following related service bulletins to correct this action: SB 80-0318, dated October 24, 2011; SB no. 80-0318, revision 1, dated February 3, 2012; and SB 80-0318, revision 2, dated March 28, 2012.

The FAA estimates that the proposed AD would affect 110 aircraft registered in the US at a cost of $3,280 per product, or $360,800 total. This per-aircraft total includes the required parts, which would cost $2,770 per aircraft, and six hours of labour at an estimated rate of $85 per work-hour. The FAA says that Piaggio Aero Industries may cover some costs under warranty.

The FAA is proposing this AD because the agency determined that this unsafe condition exists and is likely to either be present or to develop in other US-registered aircraft. The FAA will accept comments for 45 days after 14 June.

Source: Air Transport Intelligence news