Airworthiness Directives; Honeywell International, Inc. (Type Certificate Previously Held by AlliedSignal, Inc. and Textron Lycoming) Turboshaft Engines

The FAA is superseding Airworthiness Directive (AD) 2002-03- 01, which applied to certain Honeywell International, Inc. (Honeywell) T53 model turboshaft engines. AD 2002-03-01 required initial and repetitive special vibration tests of the engine and, if necessary, replacement with a serviceable reduction gearbox assembly, or a serviceable engine before further flight. This AD was prompted by reports of tachometer drive spur gear failure, resulting in potential engine overspeed, loss of power turbine speed (N2) instrument panel indication, and hard landings. This AD requires initial and repetitive special vibration tests of the engine and, depending on the results, replacement of either the reduction gearbox assembly or the engine. The FAA is issuing this AD to address the unsafe condition on these products.