Eurocopter AS 355 (Twin Ecureuil) Series Helicopters

AD/AS 355/75 MGB Free-Wheel 3/2004 DM

Applicability: AS 355 E, F, F1, F2 and N model helicopters fitted with a main gearbox (MGB) incorporating:
1. A bevel reduction gear supplied or installed by Eurocopter Marignane; and/or
2. A combiner gearbox supplied or installed by Eurocopter Marignane; and
3. Has less than 10 hours flying time in service since installation of an applicable bevel reduction gear or combiner gearbox.

Requirement: 1. Replace the combiner gearbox; or
2. Clean the combiner gearbox in accordance with a DGAC approved Eurocopter Technical Support Directorate published procedure.

Note: DGAC Airworthiness Directive Number F-2003-454 refers.

Compliance: Effective 21 January 2004; before further flight. This Airworthiness Directive becomes effective on 21 January 2004.

Background: This directive has been issued to address a report of an engine overspeed event involving an AS355 helicopter during the single engine phase of an acceptance flight. The engine overspeed resulted from free-wheel clutch slippage due to insufficient cleaning of preservation fluid from the MGB.

FMI: www.casa.gov.au/avreg/aircraft/ad/ADfiles/Rotor/as355/AS355-075.pdf