AD/Thielert/11 Amdt 1 Propeller Control Valve Life Limit (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/THIELERT/11 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.

Thielert Piston Engines

AD/THIELERT/11 Amdt 1 Propeller Control Valve - Life Limit 11/2008 DM

Applicability:

Thielert Aircraft Engines (TAE) GmbH TAE125-01 and TAE 125-02-99 engines, installed on Diamond Aircraft Industries Model DA 42 aircraft.

Requirement:

1.    For TAE 125-01 engines: Replace the propeller control valve part number (P/N) NM-0000-0124501 in accordance with TAE Service Bulletin (SB) TM
TAE125-0018 or later NAA approved revision.

2. For TAE 125-02-99 engines: Replace the propeller control valve part number (P/N) NM-0000-0124501 in accordance with TAE SB TM TAE125-1007 P1 or later NAA approved revision.

Note:  EASA AD 2008-0145 dated 1 August 2008 refers.  This AD supersedes EASA AD 2008-0130.

Compliance:

For Requirement 1:

Initial replacement is required at the time indicated in Table 1 below, unless previously accomplished; and

Thereafter, repeat the replacement at intervals not to exceed 300 FH.

Table 1
Gearbox accumulated time since new:	Compliance time:
More than 400 flight hours (FH)	Within 55 FH or at the next scheduled maintenance, whichever occurs first after 29 July 2008 (the effective date of the original issue of this AD).
Less than 400 FH	Upon accumulating 300 FH (first scheduled maintenance) or within 110 FH, whichever occurs later after 29 July 2008 (the effective date of the original issue of this AD).

For Requirement 2:

Initial replacement is required at the time indicated in Table 2 below, unless previously accomplished; and

Thereafter, repeat the replacement at intervals not to exceed 300 FH.

Table 2
Gearbox accumulated time since new:	Compliance time:
More than 400 flight hours (FH)	Within 55 FH or at the next scheduled maintenance, whichever occurs first after the effective date of this AD.
Less than 400 FH	Upon accumulating 300 FH (first scheduled maintenance) or within 110 FH, whichever occurs later after the effective date of this AD.

This Amendment becomes effective on 22 August 2008.

Background:

In-flight engine shutdown incidents have been reported on Diamond Aircraft Industries DA 42 aircraft equipped with TAE125-01 engines.  Preliminary investigations showed that it was mainly the result of failure of the propeller control valve.  This condition, if not corrected, could lead to further cases of engine in-flight shutdown, possibly resulting in reduced control of the aircraft.

For the reasons stated above, this AD introduces a life limit of 300 FH for the Proportional Pressure Reducing Valve 24V P/N NM-0000-0124501 and requires the replacement of propeller control valves that have exceeded the established life limit.

As this problem has only manifested itself on this engine installed on Diamond Aircraft Industries DA 42 aircraft, TAE125-01 engines installed on other aircraft are not affected.

This amendment retains the requirements of the original AD and expands the applicability to include TAE 125-02-99 engines on Diamond DA 42 aircraft that have the affected valve installed.

The original issue of this AD became effective on 29 July 2008.

James Coyne
Delegate of the Civil Aviation Safety Authority

18 August 2008