AD/CFM56/29 25 Degree Mid-span Shroud Fan Blades (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.

CFM International Turbine Engines - CFM56 Series

AD/CFM56/29 25 Degree Mid-span Shroud Fan Blades 4/2009

Applicability:

CFM International (CFM) CFM56-3 turbofan engines, all serial numbers, when equipped with fan blades - with 25 degree mid-span shrouds - Part Number (P/N) 9527M99P08, 9527M99P09, 9527M99P10, 9527M99P11, and 1285M39P01, or fan blade pairs P/N 335-088-901-0, 335-088-902-0, 335-088-903-0, and 335-088-904-0.

Note 1:  These engines are known to be installed on, but not limited to, Boeing 737 series aeroplanes.

Note 2:  The installation of fan blades with 25 degree mid-span shrouds is not allowed on the CFM56-3C engine model.

Requirement:

1.    Perform an inspection of fan blades P/N 9527M99P08, 9527M99P09, 9527M99P10, 9527M99P11, and 1285M39P01, or fan blade pairs P/N
335-088-901-0, 335-088-902-0, 335-088-903-0, and 335-088-904-0 in accordance with paragraphs 3.A (On-wing) or 3.B (In-shop) of CFM Service Bulletin (SB) CFM56-3/3B/3C 72-1067 original issue.

Accomplishment of inspections done in accordance with CFM SB
CFM56-3/3B/3C S/B 72-1067 original issue, within the last 3,000 engine Flight Cycles (FC) before the effective date of this AD satisfies Requirement 1 of this AD.

2.    If any damage is found, remove and replace the blades as instructed in the accomplishment instructions of CFM SB CFM56-3/3B/3C SB 72-1067 original issue.

3.    Repeat the inspections detailed in Requirement 1 of this AD.

4.    Do not install on any CFM56-3 engine fan blades P/N 9527M99P08, 9527M99P09, 9527M99P10, 9527M99P11, and 1285M39P01, or fan blade pairs P/N 335-088-901-0, 335-088-902-0, 335-088-903-0, and 335-088-904-0 unless they have been previously inspected in accordance with paragraph 3 of the accomplishment instructions of CFM SB CFM56-3/3B/3C 72-1067 original issue.

The use of later approved revisions of the referenced service bulletin is acceptable for compliance with the requirements of this AD.

Note 3:  EASA AD 2009-0036 dated 20 February 2009 refers.

Compliance:

For Requirement 1 - Within 3 months after the effective date of this AD.

For Requirement 2 - Before further flight.

For Requirement 3 - At intervals not to exceed 3,000 engine FC from the last inspection.

For Requirement 4 - After the affective date of this AD.

This Airworthiness Directive becomes effective on 9 April 2009.

Background:

An event of multiple fan blade failure has been reported on a CFM56-3 engine.  Severe wear was observed on the underside of the fan blade platforms at the contact location with the fan blade dampers.  This resulted in poor damping of the fan blade set and contributed to high dynamic stress of the blades.

For the reasons stated above, this AD requires repetitive inspections of fan blades with 25 degrees mid-span shrouds as defined by CFM SB CFM56-3/3B/3C SB
72-1067 in order to reduce the risk of a multiple fan blade failure event which could result in an uncontained engine rotor failure.

James Coyne
Delegate of the Civil Aviation Safety Authority

27 February 2009