AD/PHS/15 Amdt 5 - Servo Ballscrew Internal Spline Wear (Cth)

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES

Propellers - Variable Pitch - Hamilton Standard

AD/PHS/15 Amdt 5

Servo Ballscrew Internal Spline Wear 2/96

Applicability: All 14RF-9, -19, -21, -23, 247F-1, 14SF-5, -7, -11, -15, -17, -19, -23, 14SFL11 and 6/5500/F propellers installed on but not limited to Embraer EMB-120, EMB-120RT, SAAB-SCANIA SF340B, Aerospatiale ATR42-100, -300, -320, ATR72, -210, De Havilland DHC-8-100 series, -300, Construcciones Aeronauticas SA (CASA) CN- 235, CN-235-100, Canadair CL215T, CL415 and British Aerospace ATP aircraft.

Requirement: Action in accordance with paragraphs (a) to (d) and (g) of FAA AD 95-22-12 Amdt 39-9420.

Note 1: FAA AD 95-22-12 amdt 39-9420 supersedes FAA AD 94-22-12 Amdt 39-9062, FAA AD 93-16-02 amdt 39-8659 and FAA AD 92-08-03 amdt 39-8214.

Note 2: Brazilian Telegraphic AD No T903-03 R1 and BLA AD 94-156 (AB) refer to Amdt 4 of this Directive.

Compliance: As specified in the Requirement Document with a revised effective date of 5 February 1996.

Background: The manufacturer has received reports that excessive wear has been observed in the servo ballscrew splines of the propeller control unit (PCU). This wear, if not corrected, could affect the aircraft airworthiness.

Amendment 1 was raised after receipt of advice that a Dash 8 lost control of a propeller after landing. During the subsequent investigation extreme wear was discovered on the internal splines of the PCU. These splines had previously been inspected some 750 hours prior to the incident.

Amendment 2 clarified the inspection requirements for PCU's that had operated more than 1800 hours time in service.