AD/TPE 331/63 Amdt 2 Fuel Control Unit Drive Spline (Cth)

AIRWORTHINESS DIRECTIVE

On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/TPE 331/63 Amdt 1 and issues the following 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.

AlliedSignal (Garrett/AiResearch) Turbine Engines - TPE 331 Series

AD/TPE 331/63 Amdt 2 Fuel Control Unit Drive Spline 24/2012

Applicability: 

Honeywell International Inc. TPE331-1, -2, -2UA, -3U, -3UW, -5, -5A, -5AB, -5B,
-6, -6A, -10, -10AV, -l0GP, -10GT, -l0P, -10R, -l0T, -l0U, -10UA, -10UF, -10UG,
-10UGR, -10UR, -11U, -12JR, -12UA, -12UAR, and -12UHR turboprop engines with the part numbers (P/Ns) of Woodward fuel control unit (FCU) assemblies, listed below, installed.

TPE331-l, -2, and -2UA Series Engines

Fitted with Woodward FCU assemblies, P/Ns 869199-13/ -20/ -21/ -22/ -23/ -24/
-25/ -26/ -27/ -28/ -29/ -31/ -32/ -33/ -34, and -35.

TPE331-3U, -3UW, -5, -5A, -5AB, -5B, -6, -6A, -10AV, -10GP, -10GT, -10P and l0T Series Engines

Fitted with Woodward FCU assemblies, P/Ns 893561-7/ -8/ -9/ -10/ -11/ -14/ -15/
-16/ - 20/ -26/ -27, and -29, and P/Ns 897770-1/ -3/ -7/ -9/ -10/ -11/ -12/ -14/ -15/ -16/ -25/ -26/, and -28.

TPE331-l0, -10R, -l0U, -10UA, -10UF, -10UG, -10UGR, -10UR, -11U, -12JR,
-12UA, -12UAR, and -12UHR Series Engines

Fitted with Woodward FCU assemblies, P/Ns 897375-2/ -3/ -4/ -5/ -8/ -9/ -10/ -11/
-12/ -13/ -14/ -15/ -16/ -17/ -19/ -21/ -24/ -25/ -26, and -27, and P/Ns 897780-1/
-2/ -3/ -4/ -5/ -6/ -7/ -8/ -9/ -10/ -11/ -14/ -15/ -16/ -17/ -18/ -19/ -20/ -21/ -22/
-23/ -24/ -25/ -26/ -27/ -30/ -32/ -34/ -36/ -37, and -38, and P/Ns 893561-17/ -18, and
-19.

Requirement:

1.    Initial inspection of engines with affected FCU assemblies

a.     Perform an initial dimensional inspection of the fuel control drive for wear or damage.  Information on spline inspection can be found in Section 72-00-00 of the applicable maintenance manuals.

b.    Repair or replace the fuel pump, if the spline fails the dimensional inspection, with any serviceable fuel pump.

c.     Repair or replace the FCU assembly, if the splines fail the dimensional inspection, with a serviceable modified FCU assembly.

2.    Repetitive inspections of engines with affected FCU assemblies

a.     Perform repetitive dimensional inspections of the fuel control drive, for wear or damage.  Information on spline inspection can be found in Section
72-00-00 of the applicable maintenance manuals.

b.    Repair or replace the fuel pump, if the spline fails the dimensional inspection, with any serviceable fuel pump.

c.     Repair or replace the FCU assembly if the splines fail the dimensional inspection, with a serviceable modified FCU assembly.

Definitions:

For the purposes of this AD:

A “serviceable, modified FCU assembly” for engines affected by this AD is an FCU assembly with a P/N not listed in this AD.

The “fuel control drive” is a series of mating splines located between the fuel pump and fuel control governor, consisting of the following four drive splines:  The fuel pump internal spline, the fuel control external “quill shaft” spline, and the stub shaft internal and external splines.

Note 1:  Information pertaining to operating recommendations for applicable engines after a fuel control drive failure is contained in OI 331-12R6 dated 26 May 2009, for multi-engine aeroplanes and in OI 331-18R4 dated 26 May 2009, for single-engine aeroplanes.

Note 2:  FAA AD 2006-15-08 Amdt 39-14688 dated 14 July 2006 and FAA AMOC letter 140L-11-346, dated October 6, 2011 refers (FAA AMOC relates to continued 1,000 hour inspections in lieu of mandatory FCU modification by 31 December 2012).

Compliance:

1.    Remains unchanged as detailed in the original issue of this AD as: At the next scheduled inspection of the fuel control drive, but within 1,000 hours-in-service after 28 September 2006, unless previously accomplished.

2.    Repeat intervals of 1,000 hours since last dimensional inspection of the fuel control drive spline.

This Amendment becomes effective on 6 December 2012.

Background:

This AD results from reports of loss of fuel control unit drive leading to engine overspeed, over torque, uncontained rotor failure and asymmetric thrust in multi-engine aeroplanes.  The actions detailed in this AD are to prevent destructive overspeed that could result in uncontained rotor failure and damage to the aeroplane.

This amendment is issued to:

(1)   Incorporate the intent of FAA AMOC letter 140L-11-346, dated October 6, 2011 which allows continued 1,000 hour inspections in lieu of a mandatory calendar time component removal and modification.  Requirements 3, 4 and 5 of the previous amendment that required mandatory installation of a modified FCU assembly, have been removed, in line with the FAA AMOC.

(2)   The optional method of compliance for TPE331 engines installed on single-engine aircraft is removed as it is now redundant because requirement 2 allows continued inspections and requires replacement of the fuel pump or FCU assembly if the splines fail the dimensional inspection, per FAA AMOC letter 140L-11-346.

(3)   The AMOC relating to the use of Honeywell Service Bulletin
TPE331-A73-0271 Rev 2 is now redundant as this bulletin is now at
Revision 3.  Mention of this AMOC has now been removed from the AD.  Operators and Maintainers should check that this does not affect any previous exclusions provided by CASA.

(4)   Corrects note 1 to include the latest operating recommendation for applicable engines after a fuel control drive failure.

Amendment 1 of this AD became effective on 23 June 2008.

The original issue of this AD became effective on 28 September 2006.

Mike Higgins
Delegate of the Civil Aviation Safety Authority

29 November 2012