ALERT SERVICE BULLETIN

EC135

CHANGE INSTRUCTION NO. 2 FOR EC135-63A-013

2008-09-12 PAGE 1 of 1

Date: First issue: 2008-09-10

Revision 01: 2008-09-12

Revision 02: 2008-09-12

Please replace Revision 01 of Alert Service Bulletin EC135-63A-013 with Revision 02.

With Revision 02 a printing error was corrected in Section 3.B.(7).

The dimension given in this section was corrected from 0.5 mm to 0.05 mm.

ALERT SERVICE BULLETIN

EC135

EC135-63A-013

PAGE 1 of 6

2008-09-10

REVISION 02, 2008-09-12

Main Rotor Drive – Main Transmission – Check of screws at the lower

hub–shaft bearing for correct attachment

1. Planning Information

A. Effectivity

(1) Helicopters affected: EC135/EC635, all models with main transmission 

S/N 0001 to 1420 and 1500 to 1749.

(2) Components affected: P/N 4649 010 003, 4649 010 005, 

4649 010 006, 4649 010 006X, 4649 010 008, 

4649 010 008X, 4649 001 007 and 4649 010 010.

(3) Spare parts affected: see 1.A.(2)

B. Concurrent Requirements

Not applicable.

C. Reason

Unusual vibrations occurred during the start phase of the main rotor on one helicopter. These

vibrations stopped after the application of torque. The troubleshooting accomplished by the

maintenance personnel showed that six of the eight attachment screws of the lower

hub–shaft bearing support had loosened. After the affected operator’s fleet had been

inspected, two more main transmissions were found on which the screws of the lower

hub–shaft bearing support had loosened.

The lower hub–shaft bearing consists of a ball bearing and a roller bearing. The outer race

of the roller bearing is fixed to the housing with screws. If all attachment screws should

become loose, the outer race of the roller bearing might drop down. However, the axial

guidance of the rotor hub–shaft is still ensured.

D. Description

Remove interior panelling. Drain oil, secure attachment hardware by means of locking

washers.

E. Compliance

(1) If unusual vibrations are detected during the start or the end phase of the main rotor’s

running the attachment hardware must be secured with locking washers i.a.w. Section

3.B. of this Alert Service Bulletin no later than 3 flights after receipt of this Alert Service

Bulletin.

(2) The securing of attachment hardware i.a.w. Section 3.B of this Alert Service Bulletin

must be accomplished within the next 50 fh after receipt of this Alert Service Bulletin,

but by 31.03.2009 at the latest.

This document is available on the internet: www.eurocopter.com/techpub
ALERT SERVICE BULLETIN

EC135

EC135-63A-013

PAGE 2 of 6 REVISION 02, 2008-09-12

2008-09-10

(3) If the first issue of the Alert Service Bulletin has already been accomplished, the

attachment hardware must be secured i.a.w. Section 3.B of this Alert Service Bulletin

after 400 fh (plus a tolerance of 40 fh) at the latest.

(4) The main transmissions in stores are to be secured i.a.w. Section 3.B before their

installation at the latest.

F. Approval

The technical content of this document is approved under the authority of

DOA No. EASA.21J.034.

G. Manpower

– without EMS equipment: 4 h

– with EMS equipment: 8 h

H. Weight and Balance

Not applicable.

I. Electrical Load Data

Not applicable.

J. Software Accomplishment Summary

Not applicable.

K. References

– AMM EC135

– AMM EC135/635

L. Other publications affected

Not applicable.

M. Interchangeability of Parts

Not applicable.

2. Material Information

A. Material – Price and Availability

Not applicable.

B. Support Information

On receipt of the completed reply form sheet of page 6, retrofit kit EC135–63–011–2C3,

which contains 12 liters of lubricating oil (CM 1001) will be provided free of cost. Should the

main transmission still be filled with CM103 the retrofit kit EC135-63-011-2C2 (Retrofit

modification for the use of CM1001) is available on special terms. Further information will

be provided by ECD, Dept. Spares Order Administration on request.
ALERT SERVICE BULLETIN

EC135

EC135-63A-013

PAGE 3 of 6

2008-09-10

REVISION 02, 2008-09-12

C. Material Necessary for Each Helicopter

Material kit SB-135-63A-013-2C.

No. New P/N Keyword Old P/N Qty Disposition

1 0634313686 O−ring 0634313686 1 A

2 0639021002,

alternatively

0639021005

Locking washer LN9023B6

alternatively

Locking washer LN9023A6

both in material 1.4544.9

− 8 A

Disposition:

A = New, included in kit, the O–ring can be reused once.

D. Material Necessary for Each Spare

See Section 2.C.

E. Reidentified Parts

Not applicable.

F. Special Tooling

Not applicable.

3. Accomplishment Instructions

A. Preliminary work steps:

NOTE If the transmission oil is drained into a clean container, it can be reused.

(1) Remove lower transmission cover i.a.w. AMM, 63-21-00, 4-13.

B. Secure attachment screws (1, Figure 1) using locking washers (7):

(1) Measure clearance , Figure 1 between bearing outer race (2) and transmission

housing at four positions offset by 90 degrees using a feeler gauge:

(a) If the measured maximum clearance is less than or equal to 0.1 mm, proceed i.a.w.

Section 3.B.(3).

(b) If the measured maximum clearance is more than 0.1 mm, the difference between

the smallest and the biggest clearance must be determined:

– If the difference is less than 0.4 mm, proceed i.a.w. Section 3.B.(2).

– If the difference is equal to or more than 0.4 mm, the bearing must be

replaced. To do so, send main transmission to the manufacturer for repair.
ALERT SERVICE BULLETIN

EC135

EC135-63A-013

PAGE 4 of 6 REVISION 02, 2008-09-12

2008-09-10

WARNING IF SCREWS ARE MISSING, SEARCH AND FIND THEM.

NOTE Not damaged screws can be reused.

(2) Lift helicopter i.a.w. AMM, 07–00–00, 2–1 until landing gear is relieved.

(3) Torque–tighten all screws to 9 Nm.

(4) Successively put a locking washer (7) under all 8 screws i.a.w. Figure 1.

(5) Crosswise torque–tighten all screws to 9 Nm.

(6) Bend all locking washers i.a.w. Figure 1.

(7) Measure clearance , Figure 1 between bearing outer race (2) and transmission

housing using a feeler gauge. The clearance has to be less or equal to 0.05 mm.

C. Conclusive work:

NOTE If the O–ring on the lower transmission cover is not damaged, it can be

reused once.

(1) Install lower transmission cover i.a.w. AMM, 63-21-00, 4-13.

(2) Replenish oil i.a.w. AMM, 63-21-00, 3-2.

(3) Copy reply form sheet on page 6, fill out and send to ECD customer support 

Fax: +49–906–71–4111 or 

E–Mail: maintransmission@eurocopter.com

D. Confirm accomplishment of this Alert Service Bulletin by an entry in the log card of the main

transmission.

– ASB EC135-63A-013, Rev.02 accomplished, all screws secured by means of

locking washers.

4. Appendix

Not applicable.
ALERT SERVICE BULLETIN

EC135

EC135-63A-013

PAGE 5 of 6

2008-09-10

REVISION 02, 2008-09-12

Lower Hub–Shaft Bearing

Figure 1

1 Attachment screw

2 Bearing outer race

3 Roller bearing

4 Hub–shaft nut

5 Retainer ring

6 Ball bearing

7 Locking washer LN9023 B6 / A6

Measure clearance of bearing outer race to the housing at four positions using a

feeler gauge

1 2 3 4 5

6

7
ALERT SERVICE BULLETIN

EC135

EC135-63A-013

PAGE 6 of 6 REVISION 02, 2008-09-12

2008-09-10

Reply form sheet for ASB EC135-63A-013 “Attachment of screws of the lower hub–shaft

bearing”

Completely fill out this form sheet and send by FAX to +49 906 714111 or by email to

maintransmission@eurocopter.com.

Please copy page! Original remains in Alert Service Bulletin!

Loose screws? No Yes Number

Customer Contact (Name) Telephone

Telefax

E–Mail

Operator

Helicopter S/N Helicopter Total Time TT

Main transmission S/N

Important data regarding helicopter

 Important data regarding main transmission

Main transmission TT

Main transmission TSO Main transmission P/N

Printed name

ASB EC135-63A-013 Revision 02 accomplished

Date Signature

Dropped out screws?

Remarks:

Address for material kit EC135-63-011-2C3 (see Section 2.B. of the ASB)

3

5

8

7

2

1

6 4

Mark position:

Secured with 8 locking washers?

LH RH

No Yes Number

No Yes

FLIGHT DIRECTION