AD/EC 135/17 Main Gearbox Oil Sampling & Analysis (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.

Eurocopter EC 135 Series Helicopters

AD/EC 135/17 Main Gearbox Oil Sampling & Analysis 8/2008 TX

Applicability:

Eurocopter Deutschland (ECD) GmbH EC135 and EC635 helicopters.

Requirement:

1.    For EC135 and EC635 series helicopters with serial numbers (s/n) up to 504 inclusive that have not been modified in accordance with ECD Service Bulletin (SB) EC135-63-011 (retrofit to a more efficient lubricating oil), take the first oil sample in accordance with the instructions of ECD ASB EC135-63A-012 Revision 3 dated 16 June 2008.

2.    For EC135 and EC635 series helicopters with s/n up to 504 inclusive that have been modified in accordance with ECD SB EC135-63-011, take the first oil sample in accordance with the instructions of ECD ASB EC135-63A-012 Revision 3.

3.    For EC135 and EC635 series helicopters with s/n 505 and up, take the first oil sample in accordance with the instructions of ECD ASB EC135-63A-012 Revision 3.

4.    After taking the first oil sample, take further oil samples, in accordance with the instructions of ECD ASB EC135-63A-012 Revision 3.

5.    Accomplish the analysis in accordance with the instructions of paragraph 3.A(4) of ECD ASB EC135-63A-012 Revision 3 and, depending on the results, take the corrective measures as specified and at the time(s) indicated in paragraph 3.A(5) of ECD ASB EC135-63A-012.

6.    Oil sampling, analysis and corrective actions accomplished prior to the effective date of this AD in accordance with ECD ASB EC135-63A-012 at original issue or Revision 1 or Revision 2 are acceptable to comply with the initial requirements of this AD.  After the effective date of this AD, oil sampling, analysis and corrective actions must be accomplished in accordance with ECD ASB EC135-63A-012 at Revision 3.

7.    Check the log card of the MGB for entries regarding chip indications and, depending on the results, at the time(s) indicated in paragraph 3.B of ECD ASB EC135-63A-012 Revision 3, accomplish the tasks and take the corrective measures in accordance with paragraph 3.C of ECD ASB EC135-63A-012 Revision 3.

8.    In the case of a chip detector indication, accomplish the tasks and take the corrective measures in accordance with paragraphs 3.B and 3.C of ECD ASB EC135-63A-012 Revision 3.

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

Note:  EASA AD 2008-0116-E dated 17 June 2008 refers.

Compliance:

For Requirement 1 - Within the next 100 flight hours (FH) after the effective date of this AD.

For Requirement 2 - Within the next 100 FH after the effective date of this AD, but not prior to accumulating 100 FH after accomplishment of SB EC135-63-011.

For Requirement 3 - Within the next 100 FH, but not prior to accumulating 90 FH after the first oil change, whichever occurs later after the effective date of this AD (the first oil change must be accomplished when 50 FH have been accumulated since new).

For Requirement 4 - At intervals not to exceed 100 FH (+/-10%) or 12 months, whichever occurs first.

For Requirement 5 - Before the helicopter accumulates 25 FH after taking each oil sample.

For Requirement 6 - From the effective date of this AD.

For Requirement 7 - Before further flight, when a MGB is installed that has accumulated 300 FH or more total time, or time since overhaul or since repair.

For Requirement 8 - From any time after the effective date of this AD, at the time(s) indicated in paragraph 3.B of ECD ASB EC135-63A-012.

This Airworthiness Directive becomes effective on 25 June 2008.

Background:

Following several chip indications, a main gearbox was returned to the manufacturer of the main gearbox, ZF Luftfahrttechnik (ZFL), for repair.  During disassembly, a partial tooth rupture was detected after removal of a drive pinion.  This tooth rupture was determined to have been caused by wear.

To monitor the condition of the main gearbox (MGB), Eurocopter Deutschland (ECD) has developed a program for oil samples to be taken and analyzed at regular intervals, which will ensure that wear is detected in time, prior to actual tooth rupture, and appropriate corrective measures are taken following chip indication(s).

James Coyne
Delegate of the Civil Aviation Safety Authority

19 June 2008