AD/As 355/67 Amdt 5 Main Gearbox Lubrication Pump (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/AS 355/67 Amdt 4 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.
Eurocopter AS 355 (Twin Ecureuil) Series Helicopters
| AD/AS 355/67 Amdt 5 | Main Gearbox Lubrication Pump | 12/2007 DM |
Applicability: | Eurocopter AS 355 E, F, F1, F2 and AS 355 N helicopters, equipped with lubrication pumps Part Number (P/N) 355A32-0700-01, 355A32-0700-02 or 355A32-0701-00 installed on the Main Gearbox (MGB). |
Requirement: | 1. Inspect the MGB magnetic plug and MGB oil sight glass in accordance with Paragraph 2.B.1 of Eurocopter AS 355 Alert Service Bulletin (ASB) No. 05.00.40R2 dated 20 December 2006, or later DGAC approved revisions. Requirement 1 of this AD may be carried out and certified by the pilot provided the pilot has completed an approved training program. 2. Depending on the results of the inspection as detailed in Requirement 1 of this AD, comply with Paragraph 2.B.2. of ASB 05.00.40R2 or later DGAC approved revisions. 3. For pumps listed in the Applicability section of this AD that have logged flying hours since new, overhaul or repair, comply with paragraph 2.B.2. of ASB 05.00.40R2 or later DGAC approved revisions. 4. Inspect the oil pump for wear in accordance with paragraph 2.B of EUROCOPTER AS355 ASB No. 05.00.51. The flight immediately prior to each inspection needs to last more than 20 minutes to ensure the MGB oil temperature has stabilized. After implementation of the inspection program in accordance with Requirement 4 of this AD, the ALF-checks and follow-on actions as detailed in Requirements 1, 2 and 3 of this AD may be discontinued. If the recorded value is in zone 1 (see Figure 1 of the ASB), at intervals not to exceed 110 Flight Hours (FH), inspect the oil pump for wear in accordance with the instructions specified in paragraph 2.B of EUROCOPTER AS355 ASB No. 05.00.51. |
| If the recorded value is in zone 2, at intervals not to exceed 25 FH, inspect the oil pump for wear in accordance with the instructions specified in paragraph 2.B of EUROCOPTER AS355 ASB No. 05.00.51. If the recorded value is in zone 3, before next flight, replace the oil pump with an airworthy part. 5. Inspect the oil pump for wear in accordance with the instructions specified in paragraph 2.B of EUROCOPTER AS355 ASB No. 05.00.51. This is applicable to lubrication pumps installed as part of a MGB assembly replacement or installed separately on the helicopter, This flight needs to last more than 20 minutes to ensure the MGB oil temperature has stabilized. Note: EASA AD 2007-0209-E dated 6 August 2007 refers. This AD supersedes EASA Emergency AD 2006-0378-E. | |
Compliance: | 1. Remains unchanged as detailed in amendment 4 of this AD as: Repetitively, following the last flight of the day, but no later than 10 hours time in service since last inspection. 2. Before further flight after the effective date of this AD. 3. Before installation of the lubrication pump on a helicopter. 4. Within the next 25 FH and thereafter at intervals as indicated in Requirement 4 of this AD, depending on inspection results. 5. Immediately after the first flight following installation on a helicopter of a spare lubrication pump, having P/N 355A32-0700-01, 355A32-0700-02 or 355A32-0701-00. |
| This Amendment becomes effective on 12 November 2007. | |
Background: | DGAC France issued Airworthiness Directive F-2006-027 following four reports of MGB lubrication pump deterioration. These cases had occurred on pumps with serial numbers relatively close to each other and with few (less than 610) operating hours. That AD required monitoring of MGB oil pumps, limited to those serial numbers corresponding to a machining modification concerning the shape of the pump casing. A further incident occurred on a MGB fitted with a pump that had not been subject to this machining modification. This event showed that the machining modification of the pumps was not the only reason for early deterioration of the oil pumps. After a period of operation with insufficient lubrication, the Combining Gearbox assembly can deteriorate. This condition, if not corrected, could result in the loss of the drive train from one or possibly both engines (deterioration of the combiner gearbox gears). |
| Amendment 5 adds a requirement which mandates a procedure developed by EUROCOPTER for monitoring the (condition of the) MGB lubrication pump. This procedure replaces the monitoring procedures described by EUROCOPTER AS355 ASB No. 05.00.40, now at Revision 3. Amendment 4 was issued following a further incident that occurred on an MGB fitted with a pump that had not been subject to this machining modification. This event showed that the machining modification is not the only reason for early deterioration of the oil pumps and makes the monitoring of all the oil pumps mandatory. After a period of operation of insufficient lubrication, the Combining Gearbox assembly could deteriorate resulting in the loss of the drive train from one or possibly both engines (deterioration of the combiner gearbox gears). Amendment 4 while retaining the basic requirements extended the applicability to all the pumps mentioned in the Applicability and required compliance with latest Revision of the referenced Service Document. This amendment became effective on 22 December 2006. Amendment 3 added additional serial number MGB pumps to the Applicability section and amended Requirement 3. Amendment 3 of this AD became effective on 23 November 2006. Amendment 2 changed the Applicability section of the AD by incorporating additional details in that section. Amendment 2 of this AD became effective on Amendment 1 reflected updated information from the regulatory authority and the manufacturer. Amendment 1 of this AD became effective on 17 April 2003. This Directive was originally issued to require the daily inspection of the helicopter main gearbox for evidence of impending failure of the gearbox lubrication pump. The requirement reflects four reports of evidence of lubrication pump deterioration traced to a manufacturing defect. Failure of the lubrication pump could result in the loss of gearbox drive train for one or both engines. The original issue of this AD became effective on 10 July 2002. |
David Punshon
Delegate of the Civil Aviation Safety Authority
8 October 2007
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