AD/S-92/5 Tail Rotor Pitch Change Bearing Assembly (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Sikorsky S-92 Series Helicopters

AD/S-92/5 Tail Rotor Pitch Change Bearing Assembly 11/2007 TX

Applicability:

Model S-92A helicopter, with a tail rotor pitch change shaft and bearing assembly (shaft and bearing assembly) part number 92358- 06303-041, installed.

Requirement:

1.    Borescope inspect as follows:

a)    Inspect each affected shaft and bearing assembly at tail rotor side by following the Accomplishment Instructions, paragraphs 3.A.(1) through (7) and Figure 4 of Sikorsky Aircraft Corporation Alert Service Bulletin (ASB) No. 92-64-002, dated 3 August 2007.

b)    Inspect each shaft and bearing assembly on the servo side through the oil filler cap by following the Accomplishment Instructions, paragraphs B.(1) through (9) and Figures 2 and 3, of the ASB.

Note 1:  Maintenance Manual SA S92A-ANM-000 pertains to the subject of this AD.

2.    Carry out the inspections detailed in Requirement 1 of this AD.

3.    If the shaft bearing fails the inspection, as detailed in Requirement 1 of this AD, replace the shaft and bearing assembly.

Note 2:  FAA AD 2007-17-05 Amdt 39-15163 dated 9 August 2007 refers.

Compliance:

1.    Within 20 hours time-in-service (TIS) after the effective date of this AD, unless previously accomplished.

2.    Between 10 and 15 hours TIS after installing a shaft and bearing assembly.

3.    Before further flight after the effective date of this AD.

This Airworthiness Directive becomes effective on 30 August 2007.

Background: This AD requires, within a specified time, borescope inspecting a certain part-numbered tail rotor pitch change shaft and bearing assembly (shaft and bearing assembly) and also inspecting after any installation.  This AD is prompted by an incident involving failure of a shaft and bearing assembly and servo clevis shaft resulting in loss of tail rotor control.  The actions specified in this AD are intended to prevent failure of a shaft and bearing assembly, loss of tail rotor pitch and yaw control, and subsequent loss of control of a helicopter.

Charles Lenarcic
Delegate of the Civil Aviation Safety Authority

27 August 2007