# eurocopter an EADS Company 

### ALERT SERVICE BULLETIN AS355 EUROCOPTER D IR ECTIO N TECHNIQUE SUPPORT 13725 MARIGNANE CEDEX F RANCE 

### CIVIL VERSION(S): E , F , F1 , F2 , N 

# ALERT SERVICE BULLETIN No. 05.00.51

SUBJECT: TIME LIMITS - MAINTENANCE CHECKS Monitoring of the MGB oil pump



### ATA: 

### 63 REVISION No. DATE OF APPROVAL

Revision 0 On : July 06 , 2007

Approved under EASA DOA No . 21J . 056 . 

# 05.00.51 This document is available on the internet : www.eurocopter.com/techpub 

### DATE OF ISSUE
2007 . 07.09

Page 1/12 2007 . 07 . 09

### ALERT SERVICE BULLETIN AS355
lcAUTIONI THE INFORMATION AND INSTRUCTIONS CONTAINED IN THIS ALERT SERVICE BULLETIN ARE INTENDED FOR MAINTENANCE PERSONNEL AND FLIGHT CREWS . 

### 1. PLANNING INFORMATION 1.A. EFFECTIVITY 1.A.1. Helicopters/Installed Equipment Helicopters equipped with main gearbox (MGB) oil pumps P/N 355A32-0700-01 , 355A32-0700-02 and 355A32-0701-00. 1.A.2 . Non-Installed Equipment Not applicable. 

### 1.B. ASSOCIATED REQUIREMENTS Not applicable . 

### 1.C. REASON To monitor the oil pump periodically for wear to prevent insufficient lubrication of the MGB. Compliance with this ALERT SERVICE BULLETIN supersedes the instructions of ALERT SERVICE BULLETIN AS355 No . 05.00.40 (mandatory check at each After Last Flight of day (ALF) check of the MGB magnetic plug and oil level sight). This ALERT SERVICE BULLETIN will be the subject of an EASA Airworthiness Directive. 

### 1.D. DESCRIPTION Following an incident in late 2006 , EUROCOPTER issued Revision 2 of ALER T SERVICE BULLETIN No. 05.00.40 on December 20 , 2006 , to extend its effectivity to all the part numbers of the oil pumps . Th i s ALERT SERVICE BULLET I N r eq ui red mon i toring o f t he magne t i c pl u g an d t he c olo r o f t h e o il a t eac h ALF c hec k. Since then , EUROCOPTER has studied a procedure for detecting any oil pump wear as early as possible in order to reduce the risks of helicopter downtime . Oil pump wear is a slow-acting phenomenon that causes a progressive drop of pressure in the oil system over time . 

### Approved under EASA DOA No . 21J . 056 . 

# 05.00.51 Page 2/12 2007.07 . 09

# eurocopter an EAOS Company 

### ALERT SERVICE BULLETIN AS355 During helicopter starts , the oil system pressure increases with the rotor RPM (NR). As t he wear of the oil pump increases , its efficiency drops. In successive starts , the oil p ressure ind ica tor light ther efore extinguishes la ter and la ter, occ urr ing at higher and higher rotor RPM (NR). The pressu re in the oil system also varies with the oil tem perature , which is itse l f variable and dependen t on the Outside Air Temperature (OAT) . To determine the pressure , temperature of the oil in the MGB must therefore be steady . The procedure given in this ALERT SERVICE BULLETIN is based on these phenomena . The following values are to be recorded periodically during starting phases after the MGB oil temperature has stabilized: the NR value at which the MGB oil pressure i ndicator light goes out , and the outside air temperature . Charts are included for determining the amount of wear on the oil pump and for defining the new measurement intervals and the removal criterion for the pump . EUROCOPTER renders compliance with this ALERT SERV I CE BUL LETIN mandatory . 

### 1.E. COMPLIANCE 1.E.1 . Compliance at the works 1 . E .1 . a . On Helicopters : Comply with paragraph 1 . E . 2 .a. 1.E . 1 . b. On Non-Installed Equipment: Not applicable . 1 . E . 2 . Compliance in service : By the operator : 1 . E . 2 . a . On Helicopters/Installed Equipment Comply with paragraph 2 . B . within 25 fly i ng hours following receipt of this ALERT SERVICE BULLETIN, issued on the date specified in the footer , and immediately upon return from a flight lasting more than 20 minu t es, t o ensure the MGB oil temperatu re has stabil iz ed .

-Then, depending on the value measured as per paragraph 2.B.2 . :

. Measured value in ZONE 1: Comply with paragraph 2.B. at intervals not exceeding 110 flying hours OR

. Measured value in ZONE 2 : Comply with paragraph 2.B. at intervals not exceeding 25 flying hours OR

. Measured value in ZONE 3: Replace the oil pump before resuming flights. 1.E . 2 . b. On Non-Installed Equipment Comply with paragraph 2 . B . during the flight following installation of an MGB fitted with an oil pump whose P/N is defined in paragraph 1.A.1. or during the flight following installation on the MGB of an oil pump whose P/N is defined in paragraph 1.A.1.



### Approved under EASA DOA No. 21J.056 . 

# 05.00.51 Page 3/12 2007.07.09

### ALERT SERVICE BULLETIN AS355
1.F. APPROVAL Approval is limited to civil version helicopters subject to an Airworthiness Certificate . The technical information contained in this ALERT SERVICE BULLETIN was approved on 

### July 06 , 2007 under the authority of EASA Design Organisation Approval No . 21J . 056 . 

### 1.G. MANPOWER Qua l ification : Mechanic and/or flight crew . Time for the operation: Approximately 15 minutes. 

### 1.H. WEIGHT AND BALANCE Not applicable. 

### 1.1. EFFECT ON ELECTRICAL LOADS Not applicable . 

### 1.J. SOFTWARE MODIFICATION EMBODIMENT STATE Not applicable. 

### 1.K. REFERENCE DOCUMENTS Maintenance Manual (MET) Work Cards:

- 63 . 00 . 00.402 ,

- 63 . 00 . 00.403 . 

### 1.L. OTHER DOCUMENTS CONCERNED Maintenance Program ( PRE ). Flight Manual (MV) . Maintenance Manual (MET). 

### 1.M. TOOLING CONCERNED Not applicable. 

### 1.N. INTERCHANGEABILITY AND MIXABILITY OF PARTS Not applicable . 

### Approved under EASA DOA No . 21J . 056. 

# 05.00.51 Page 4/12 2007 . 07 . 09

### ALERT SERVICE BULLETIN AS355 

### 2. ACC OMP LI SHMEN T I NS T R UCT IONS 2. A . G ENERA L Not applicable . 

### 2.8. OPERATIONAL PROCEDURE 2 . B . 1 . Preliminary steps Upon return from a flight lasting more than 20 minutes to ensure the MGB oil temperature has stabilized , comply immediately with the procedure in paragraph 2 . B.2 . 2.B.2 . Oil Pump Wear Inspection Procedure 1 . Shut down the engines. 2 . Record the OAT ( ° C o r o F ). 3 . Start at least one eng i ne . 4 . Record the NR RPM at which the red MGBP oil p r essure i ndicator light goes ou t. 5 . Shut down the engine(s ) . 6 . Transfer the OAT and NR values on to the chart (see Figure 1 ( 0 C) or Figure 2 C F )) . 7 . Perform the action r equired according to the posit i on of the measurement on the charts :

- ZONE 1 ( Below curve A ), comply wi t h parag r aph 2.B . at interva l s n ot exc e eding 110 flying hours -ZONE 2 ( Between curves A and B ), comply w i th paragraph 2 . B . a t in t e rv als no t e x ceeding 25 flyi n g

hours .

- ZONE 3 ( Above c u rve B ) , r e m ove a nd r eplace t he oil pump befo r e r es u ming fligh t s , as pe r MET Wo rk

Cards 63 . 00.00.402 and 403. When the measurement is in ZONE 2 (monitoring every 25 fly i ng hours) and the following measurement is in ZONE 1 (monitoring every 110 flying hours) , two successive monitoring operations must be carried out at intervals not exceeding 25 flying hours to confi r m the measu r ed value i n ZONE 1 before going back t o t he moni t o r ing a t in te rv als n o t e x ceeding 11 0 flying h ours.
When the measurement is in ZO NE 2 (monitoring every 25 fly i ng hours): a) The possible causes for oil pressure loss are e x

plained in paragraph 4.A. (APPENDIX)



### Approved un d er E A SA DOA No . 21J . 056 . 

# 05.00.51 Pa g e 5 /12 2007.07 . 09

### ALERT SERVICE BULLETIN AS355 b) A table for y ou to record the OAT and NR values is included in

paragraph 4.8 . (APPENDIX) When the measurement is in ZONE 

### 2 (monitoring every 25 flying hours) , please send this table (once only) to the address below: EUROCOPTER Marignane , Direction Technique Support (ESTVM) 13725 Marign ane CEDEX France Tel : +33 (0)4.42.85.99 . 51 Fax: +33 (0)4 .42 . 85.99 . 66 Email : frederic . antoine@eurocopter
. com We will use this table to study the behaviour of the MGB oil pump throughout the fleet and to forecast the need for oil pump spares more accurately. 8 . Also record the OAT 

### ( • c or • F) and NR (RPM) values each time in the table in paragraph 4 . 8 . (APPENDIX) to monitor their variation. 

### 2.C. IDENTIFICATION Record the first compliance with this ALERT SERVICE BULLETIN on the oil pump logcard (FM) . 

### 2.D. OPERATING AND MAINTENANCE INSTRUCTIONS Not applicable.



### App r oved under EASA DOA No . 21J . 056 . 

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### ALERT SERVICE BULLETIN AS355 

### 3. MATERIAL INFORMATION 3.A. MATERIAL: COST- AVAILABILITY For any information on the kits and/or components, contact the EUROCOPTER Network Sales & Customer Relations Department. 

### 3.8. INFORMATION CONCERNING INDUSTRIAL SUPPORT Not applicable. 

### 3.C. EQUIPMENT REQUIRED FOR EACH AIRCRAFT/ENGINE/COMPONENT Not applicable. 

### 3.D. PROCUREMENT CONDITIONS Order the required quantity , unless otherwise specified ,

to EUROCOPTER Marignane Plant Sales & Customer Relations Department ECR. 13725 MARIGNANE CE DEX FRANCE 

### NOTE1 For ALERT SERVICE 8 ULLETINS , order by: Telex : HELl COP 410 969F . Fax : +33 (0)4.42.85.99 . 96. 

### NOTE2 On the purchase order, please specify the mode of transport , the destination , and the serial numbers of the helicopters to be modified .



### Approved under EASA DOA No . 21J.056 . 

# 05.00.51 Page 9/12 2007 . 07 . 09

### ALERT SERVICE BULLETIN AS355 

### 4. APPENDIX 4.A. POSSIBLE CAUSES FOR MGB OIL PRESSURE LOSS ' ' ' ' 

### P min ' ' ' ' 

# I 

# \ 

# + ' ' ' ' ' ' 

### Oil filter 

# I ' ' 

### Oil jets ' ' 

### ' ' ' ' ' 

### Coolers

Oil pump



# ~ Pressure relief valve



# ---------------------- The loss of oil pressure may be due to : 1 . MGB oil pump wear 2 . A clogged filter or cooler , 3 . A pinched hose , 4. An incorrectly set pressure switch .

- Check points 2, 3 and 4 when the measurement is in ZONE 2 after replacement of an oil pump or for an

oil pump which has logged a few fly i ng hours . If the oil filter has clogged up , replace it with a new filter. If the oil cooler has clogged up , use White Spirit to clean the cooler oil circuit (refer to the CMM) . If a hose is pinched , replace it with a new hose . If the operation of the oil pressure switch is in doubt , replace it with a new pressure switch.

- After compliance with points 2 to 4 , if the oil pressure is still low , please contact the EUROCOPTER

Technical Support Directorate (ESTVM) at: Tel: +33 (0)4.42.85.99.51 Fax: +33 (0)4.42.85.99.66 Email : frederic . antoine@eurocopter.com


### Approved under EASA DOA No . 21J . 056 . 

# 05.00.51 Page 10/12 2007 . 07.09

# eurocopter an EADS Company 

### ALERT SERVICE BULLETIN AS3 5 5 4.8. TABLE FOR RECORDING OAT AND NR VALU E S- OIL PUMPS CUSTOMER NAME: Address : Tel: ...... ... . .. .... .. .. .... .. . ... ...... .. .. Email: .. ............................ .. .... . .. .. . .... .. ... ...... .. . .... . HELICOPTER VERSION REGISTRATION

AS 355 

# I

P/N: OIL PUMP TYPE OF OIL 

# I S/N: DATE OF OIL PUMP MEASUREMENT ** TSO

*T SN : Time Since New. **TSO : Time Since Overhaul. 

### Approved under EASA DOA No . 21J.056 . TIME OF LAST OAT ( 0 

### C) NR (RPM) FLIGHT OAT (°F)



# 05.00.51 Page 11/12 2007 . 07 . 09

### ALERT SERVICE BULLETIN AS355 4.C. FOR INFORMATION: SEE ENCLOSED PAGE Draft of the modified page of the Flight Manual Supplement to be given to the Flight Crew Pending the rev i sion of the Flight Manual , this page must be inserted for information in the Flight Manual. Upon receipt of the revision , this Flight Manual page will no longer be applicable. Subsequent changes made to this Flight Manual page will not give rise to a revision of this ALERT SERVICE BULLETIN.



### Approved under EASA DOA No . 21J.056. 

# 05.00.51 Page 12/12 2007 . 07 . 09

## SHEET No. 

# 3 HELICOPTER 

# AS355

SUBJECT AND TEST

REQUIREMENTS COMPLEMENTARY FLIGHT MANUAL CHECKS AFTER EXCHANGING THE MGB OR THE COMBINER MODULE

MGB OIL P U MP CHECK Run-up- Hover Flight RESULTS TO BE ACHIEVED OR LIMITATIONS RESULTS ACHIEVED 

### I E ngine starti n g in comp li ance with Ext inction of the MGB P Correct Incorr ect the No rm a l Procedures of F li ght indicator li g ht at N R < 200 rpm. Manual SECT IO N 4.1.

Hover flight for 5 to I 0 min. FROM 

### 6 ft, at a we i ght c l ose to the maximum takeoffweight. See F li g h t Manual SECTION 5 .

PROC EDU RE F OR CHECK I NG THE MGB OIL P UMP Imm ediate l y o n compl et ion of a**~** 20-minu te flight.

- Rec ord the O AT Restart at least one engine .

- Record the NR upon exti nction of

the MGB P indicator light Record the values on the crossreference chart by complying with the directives of ASB 05.00.51. See Limitat i ons , Fligh t Manua l SECTION 2.1 .



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