ALERT SERVICE BULLETIN

EC135

CHANGE INSTRUCTION NO. 5 FOR EC135-63A-012

2011-09-06 PAGE 1 of 1

Date: First issue: 2007-08-08

Revision 01: 2007-12-14

Revision 02: 2008-03-31

Revision 03: 2008-06-16

Revision 04: 2009-04-27

Revision 05: 2011-09-06

Please replace Revision 04 of Alert Service Bulletin EC135-63A-012 with Revision 05.

With Revision 05 no further measures are introduced. The formerly required oil analysis feedback

to ECD will no longer be necessary. The oil analysis form sheets have been changed accordingly.

It is no longer required that the laboratory is approved by ECD, but we recommend to choose a

laboratory which is approved by ECD. The email address “maintransmission@eurocopter.com”

will be deleted.

In order to provide a better overview a table has been introduced on page 2 and the entire Alert

Service Bulletin has been divided into four parts:

Part 1: Taking of the Oil Sample

Part 2: Evaluation of the oil analysis

Part 3: Measures after chip detector indication

Part 4: Inspection of the toothing on the drive stages

This division shall make the assignment of the individual work steps clearer, e.g. all Sections

designated with “Part 1” in the Alert Service Bulletin are associated with taking the oil sample.

Starting with the “Accomplishment”, the “Accomplishment Instructions”, the associated Figures

up to the “Confirmation” of the accomplished work steps.

ALERT SERVICE BULLETIN

EC135

EC135-63A-012

PAGE 1 of 29

2007-08-08

REVISION 05, 2011-09-06

Main Rotor Drive – Main Transmission – Introduction of an oil analysis

and adaption of measures after indication of chip detector

1. Planning Information

A. Effectivity

(1) Helicopters affected: EC135/EC635, all models.

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

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

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

4649 010 013.

(3) Spare parts affected: Not applicable.

B. Concurrent Requirements

Not applicable.

C. Reason

Following several chip indications, several main transmissions were returned to the

manufacturer for repair. Within the framework of the inspection of these main transmissions,

a partial tooth rupture was detected after removal a drive pinion. This tooth rupture was a

follow–up damage caused by excessive wear.

In order to detect wear in time, with this Alert Service Bulletin an oil analysis is introduced

for monitoring the condition and the inspection measures following a chip indication are

adapted.

D. Description

Perform scheduled oil analyses on the main transmission and accomplish given procedures.

Accomplish the given measures following a chip detector indication.

This document is available on the internet: www.eurocopter.com/techpub
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E. Compliance

NOTE The following table lists an overview of the specified measures. Accomplishment of the measures

(Part 1 to Part 4) and the determined stage / water content must be confirmed by an entry in the

log card. Please find a detailed list of the measures subsequent to this Table.

Part 1 Take oil sample: 

– every 100 fh (+10 fh tolerance), at least once a year 

– if required by the analysis i.a.w. Part 3

Note: 25 fh after Part 1 the oil analysis must be accomplished i.a.w. Part 2.

Part 2 Analyze and evaluate oil sample: 

 – within 25 fh after the oil sample has been taken 

Viscosity too low (within 25 fh

after oil analysis)

Remove oil filter element and inspect it (Part 3)

Inspect toothing (Part 4)

Accomplish oil change

Water content 

between 0.1 % and 0.5 %

Perform oil change within 10 fh after the oil analysis has been accomplished

Water content 

more than 0.5 %

Accomplish oil change before the next flight

After the third entry ”water content more than 0.5 %” has been made, inspect

toothing within 50 fh after the oil analysis has been accomplished (Part 4).

Stage I No further measures required

Stage II (within 25 fh after the oil

analysis)

Remove oil filter element and inspect it (Part 3)

Inspect toothing (Part 4)

Accomplish oil change

Stage III (within 10 fh after the oil

analysis)

Remove oil filter element and inspect it (Part 3)

Inspect toothing (Part 4)

Accomplish oil change

Part 3 Analyze and evaluate chips: 

– when chip detector is indicated

Stage A Remove oil filter element and analyze chips (Stage A – D).

After stage A has been reported twice: Inspect toothing within 10 fh (Part 4).

Stage B Remove oil filter element and analyze chips (Stage A – D).

Inspect toothing within 10 fh (Part 4).

Perform ground run and then re–inspect the chip detector.

Stage C Remove oil filter element and analyze chips (Stage A – D).

Inspect toothing before the next flight (Part 4).

Take an oil sample and analyze it (Part 1 and 2).

After stage C has been reported twice: Accomplish the measures of stage D within

50 fh.

Stage D Take an oil sample (Part 1)

Collect chips for analysis.

Send main transmission with chips and oil sample / oil analysis to the manufacturer for

repair before the next flight.

Part 4 Inspect toothing on the drive stages:

– if required by the analysis i.a.w. Part 2 or Part 3

Tooth image i.a.w. Figure 11, 12, 

green area

admissible wear, no replacement required

Tooth image i.a.w. Figure 11, 12, 

red area

not admissible wear, remove main transmission and send it to the manufacturer.
ALERT SERVICE BULLETIN

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EC135-63A-012

PAGE 3 of 29

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REVISION 05, 2011-09-06

Part 1: Taking of the Oil Sample:

EFFECTIVITY EC135/EC635 up to and including S/N 0504.

1. If a previous revision of this Alert Service Bulletin has not been carried out the first oil

sample must be taken i.a.w. Section 3, Part 1 within 100 fh or one year from the last oil

change or at the next oil change (see Note).

EFFECTIVITY All EC135/EC635.

1. The first oil sample must be taken within 100 fh after the last oil change (see Note) has

been done.

2. After the first oil sample has been taken other oil samples must be taken i.a.w. Section

3, Part 1 in regular intervals within 100 fh (see Note), but at least once a year. On

accomplishment of the oil change the oil analysis is set back to 0 fh and then starts over

again.

NOTE For the taking of the oil sample a tolerance of 10% (90 fh to 110 fh) applies.

If the oil sample is carried out at same time as oil change the oil sample

is to be carried out prior to the oil change.

Part 2: Evaluate the oil analysis and start measures:

EFFECTIVITY All EC135/EC635.

1. The oil sample must be analyzed i.a.w. Section 3, Part 2 within 25 fh after the oil sample

has been taken. Prior to evaluation of the oil analysis results the helicopter may be

operated without restrictions.

Part 3: Measures after chip detector indication:

EFFECTIVITY All EC135/EC635.

1. If the chip detector indication illuminates the chip detector must be checked i.a.w.

Section 3, Part 3 of this Alert Service Bulletin and an entry in the log card of the main

transmission must be made. This Alert Service Bulletin takes precendence over the

AMM task until such time as the Alert Service Bulletin is incorporated into the AMM.

EFFECTIVITY All EC135/EC635 with a main transmission TT, TSO, TSR that has more

than 300 fh.

1. If an issue of this Alert Service Bulletin has already been accomplished before Revision

04 was issued, the log card of the main transmission must be checked immediately for

entries regarding to chip indications. If, within the last 300 fh, stage A has been entered

twice or stage B has been entered once in the log card, the toothing must be inspected

i.a.w. Section 3, Part 4 within 10 fh.
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2. In future, the toothing must be inspected i.a.w. Section 3, Part 4 within 10 fh after the

second chip detector indication i.a.w stage A or after the first chip detector indication

i.a.w stage B. Make an entry in the log card of the main transmission.

3. In future, the measures i.a.w. stage D must be accomplished within 50 fh after the

second chip indication i.a.w. stage C has occurred. 

Part 4: Inspect toothing on the drive stages:

EFFECTIVITY All EC135/EC635.

1. The toothing must be inspected i.a.w. Section 3, Part 4 whenever the measures after

the chip detection or the measures after the oil analysis require the inspection.

2. If pitting or spalling i.a.w Figure 11 or 12 is detected, during accomplishment of the

inspection i.a.w Section 3, Part 4, the transmission must be replaced before the next

flight.

F. Approval

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

DOA No. EASA.21J.034.

G. Manpower

Not applicable.

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

The changes to AMM/MSM EC135 and AMM/MSM EC135/635 which are required as a

result of this Alert Service Bulletin will be incorporated with one of the next revisions.
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REVISION 05, 2011-09-06

M. Interchangeability of Parts

Not applicable.

2. Material Information

A. Material – Price and Availability

Information on cost and availability of required retrofit kit SB-135-63A-012-2C will be

provided by ECD, Dept. Spares Order Administration on request.

B. Support Information

Not applicable.

C. Material Necessary for Each Helicopter

Retrofit kit SB-135-63A-012-2C. The material kit is needed for the inspection i.a.w. Section

3, Part 4.

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

1 0634313288 O−ring 0634313288 2 A

2 0634316171 O−ring 0634316171 2 A

Remark:

A = New, included in kit.

D. Material Necessary for Each Spare

Not applicable.

E. Reidentified Parts

Not applicable.

F. Special Tooling

– Testing probe with a ball diameter at the tip of 0.3 – 0.5 mm (dental tool, WHO

parodontometer, e.g. parodontometer P–WHO 11,5, )

– Guide bolt (made from a screw M6 with a shank length of 80 mm, see Figure 15)
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3. Accomplishment instructions

Part 1: Taking of the Oil Sample:

A. Preconditions:

– Do not refill new oil immediately before the oil analysis.

– The oil samples may not be taken directly from the transmission bottom or from the

filter housing.

– Container and sample syringe must be free of any deposits.

– Protective caps of the sample syringe and the container may only be removed

immediately before the sample is taken and must be re–installed immediately after the

sample has been taken.

– The oil must have reached its normal operating temperature (approx. 50 to 70

degrees centigrade) and well mixed. Therefore, the oil sample should be taken within

10 minutes after engine shutdown.

B. Take oil sample:

(1) Open oil filler neck (Figure 1) and remove oil filter element.

(2) Take oil sample by means of a syringe (Figure 1) and fill approx. 50 ml into the provided

bottle.

(3) It is important that the complete data is given and sent together with the oil sample for

analysis:

– S/N, TT (Total Time) and TSO (Time Since Overhaul) of the main transmission

– Operating time of the oil in fh

– Oil type

– S/N and TT of the helicopter

– Operator

– Date

C. If necessary, refill oil i.a.w. AMM, 63-21-00, 3-2.

D. Have oil analysis accomplished in a laboratory. It is recommended to choose a laboratory

that is approved by EC (see http:/www.eurocoptersea.com.sg/dlctr/laboratories.html ).

Determine proportions of iron (Fe) contained in the oil. Determine viscosity at 100_C i.a.w.

DIN 51562 and water content in weight-%.
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REVISION 05, 2011-09-06

Part 2: Evaluate oil analysis:

A. Document oil analysis:

Using Figure 2 (oil i.a.w. MIL-PRF-23699) or Figure 3 (oil i.a.w. ZFN-L-3001) and enter

values as shown in example (Figure 4). Carry out procedures according to determined stage

(I to III) and to viscosity and water content values:

NOTE If SB EC135-63-011 (retrofit to a more efficient lubricating oil) has been

accomplished recently, the increased cleansing property of the new oil

may possibly falsify the results of the oil analysis. This increased cleansing

property of the oil may separate deposits from the housing and keep them

floating. This can cause increased analysis values and also lead to more

deposits on the chip detector. Contact ECD customer support if any

clarification is required for oil sample results.

B. Viscosity:

(1) The standard value for lubricating oil i.a.w. MIL-PRF-23699 is 4.9 to 5.4 mm2/s. If the

value is below 4.9 mm2/s, accomplish measures i.a.w. stage II.

(2) The standard value for lubricating oil i.a.w. ZFN-L-3001 is at least 7 mm2/s. If the

measured value is less than the given value, accomplish measures i.a.w. stage II.

C. Water content:

The limiting value for the water content is 0.1 %. If this value is exceeded:

(1) If the water content is between 0.1 and 0.5 %, accomplish an oil change within the next

10 fh.

(2) If the water content is greater than 0.5 %, accomplish an oil change before the next

flight.

(3) Enter process in the log card of the main transmission.

– After the third entry in the log card has been made, the measures i.a.w. stage II

must be accomplished within 50 fh.

D. Stage I:

No further measures required.

E. Stage II:

The following measures are required within 25 fh:

(1) Remove oil filter element i.a.w. AMM, 63-21-00, 4-5 and inspect i.a.w. Section 3, Part 3

of this Alert Service Bulletin. Clean oil filter element i.a.w. AMM, 63-21-00, 7-2 and

install.
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(2) Have toothing inspected i.a.w. Section 3, Part 4. During this inspection the transmission

remains on the helicopter. If there is a chip detector indication within these 25 fh inspect

the chip detector i.a.w. Section 3, Part 3.

(3) Accomplish oil change.

F. Stage III:

The following measures are required within 10 fh:

(1) Remove oil filter element i.a.w. AMM, 63-21-00, 4-5 and inspect i.a.w. Section 3, Part 3

of this Alert Service Bulletin. Clean oil filter element i.a.w. AMM, 63-21-00, 7-2 and

install.

(2) Have toothing inspected i.a.w. Section 3, Part 4.

(3) Accomplish oil change.

Part 3: Measures after chip detector indication:

NOTE The findings and measures described for the chip detector (1, Figure 6) are also

effective for particles that are found in the oil filter element and the filter of the

chip detector housing (2).

A. Remove chip detector i.a.w. AMM, 63-40-00, 4-1 and analyze deposits on the chip detector

i.a.w. the following table and start measures:

Deposits i.a.w. Figure 5, stage A:

Findings Possible

causes 

Measures 

Slight abrasion Normal

wear

(a) Clean chip detector and install.

(b) Remove oil filter element i.a.w. AMM, 63-21-00,

4-5 and check for deposits and chips. Analyze

deposits. If no chips are present, clean oil filter

element i.a.w. AMM, 63-21-00, 7-2 and install.

(c) Enter the chip indication in the log card of the

main transmission.

(d) On main transmissions with TT, TSO, TSR

more than 300 fh: Inspect toothing i.a.w.

Section 3, Part 4 within 10 fh, after the second

chip indication has been indicated.
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REVISION 05, 2011-09-06

Deposits i.a.w. Figure 5, stage B:

Findings Possible

causes 

Measures 

Increased slight

abrasion, no chips

Normal

wear or first

signs of a

damaged 

transmission

(a) Accomplish measures (a) to (c) i.a.w. 

stage A.

(b) On main transmissions with TT, TSO, TSR

more than 300 fh: Inspect toothing i.a.w.

Section 3, Part 4 within 10 fh.

(c) Accomplish ground run (duration 15 min, at power

setting IDLE) and then reinspect chip detector.

Deposits i.a.w. Figure 5, stage C:

Findings Possible

causes 

Measures 

Some chips,

triangular to

trapezoidal. One

side is smooth

with still

recognizable

working structure

or scoring, the

other side with

fracture.

Damaged

gear wheel

(a) Accomplish measures (a) to (c) i.a.w. 

stage A.

(b) Inspect toothing i.a.w. Section 3, Part 4 before

the next flight.

(c) Additional take an oil sample and accomplish

oil analysis (Section 3, Part 1 and 2).

(d) After the second chip indication i.a.w. stage C

has occurred the measures i.a.w. stage D must

be accomplished no later than within 50 fh.

Deposits i.a.w. Figure 5, stage D:

Findings Possible

causes 

Measures 

Several very thin

chips which shine

bright on one side

in increased

abrasion.

Damage to

the bearing

(a) Take oil sample.

(b) Collect chips for analysis.

(c) Send main transmission with chips and oil sample

/ oil analysis to the manufacturer for repair before

the next flight.
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Part 4: Inspect toothing on the drive stages:

A. Remove drive shaft i.a.w. AMM, 63-11-00, 4-1.

B. Remove drive stage:

CAUTION DO NOT INTERCHANGE COMPONENTS OF THE LH AND RH

DRIVE STAGE. THEREFORE, ONLY ONE DRIVE SHAFT AT A

TIME MAY BE REMOVED AND INSPECTED. BEFORE THE

SECOND DRIVE STAGE IS INSPECTED, THE FIRST DRIVE

STAGE MUST BE REINSTALLED.

(1) If necessary, remove dirt and deposits from the entire circumference of the drive stage.

To do so, use a lint–free cloth or a piece of paper. Do not use cleaning solvents.

(2) Before removal, mark the position of shim (3, Figure 7), bearing (2) and cover (1)

against each other (1, Figure 8). Mark bearing housing with either LH or RH (2).

(3) Remove oil nozzle (3, Figure 8).

(4) Using hot air blower (4, Figure 8), heat housing to a maximum of 60 degrees centigrade.

NOTE Wear lint–free gloves for the removal of the drive stage.

(5) Remove six of the seven hexagon head screws (1, Figure 9). In order to secure the drive

stage, the uppermost hexagon head screw (2) remains tightened.

(6) Hold drive stage with one hand and remove the remaining hexagon head screw (2,

Figure 9).

CAUTION WHEN REMOVING THE DRIVE STAGE, IT MUST BE ENSURED THAT

THE DRIVE STAGE DOES NOT SLIP OUT, THAT THE INDIVIDUAL

PARTS – ESPECIALLY SHIM, BEARING AND COVER – ARE REMOVED

TOGETHER AND THAT THE SHAFT SEAL IN THE COVER (1, FIGURE

7) IS NOT TILTED OR TWISTED.

(7) Pull out drive stage (3, Figure 9).

(8) Protect opening of housing from contamination.

(9) Put drive stage onto flange of free wheel shaft (5, Figure 7).

(10) Secure drive stage components with two hexagon head screws (6), washers (7) and

nuts (8).

(11) In order to remove the residual oil (approx. 0.1 liters), turn drive stage by 180 degrees

and drain oil in a container. To do so, hold drive stage in this position.
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REVISION 05, 2011-09-06

(12) Position drive stage as shown in Figure 10.

CAUTION CLEANING SOLVENT MUST NOT GET INTO THE TRANSMISSION OIL.

(13) Clean toothing on the drive stage and on the bevel gear (2, Figure 10) of the

intermediate shaft using a lint–free cloth. If necessary, dry cleaning solvent CM 202 can

be used.

C. Visual inspection of the toothing (23 teeth on the drive pinion, 80 teeth on the bevel gear of

the intermediate shaft) for damage:

NOTE Factory–applied lacquer (silver or blue, Figure 13) serves for the setting

of the contact pattern and does not count as damage. Figure 11 shows a

possible kind of damage for the drive pinion and Figure 12 shows the same

for the bevel gear. Pinion and bevel gear do not have the same contact

pattern nor do they have the same position of the contact line.

(1) Using a permanent pen, mark the first tooth to be inspected on the outer race and

inspect tooth in direction of sight (Figure 11, 12). Then, turn gear wheel until all teeth

have been inspected. 

(2) Only the tooth images shown in the LH green frame are admissible (Figure 11, 12).

(3) The tooth images shown in the RH red frame (Figure 11, 12) are not admissible. These

main transmissions must be removed and sent to the manufacturer. Please send a

completed copy of the attached reply form sheet together with the main transmission.

(4) In (1, Figure 14) a pinion with a contact line is shown. This area and also other areas

which are conspicuous during the visual inspection, must be manually traced with a test

probe (2). The test probe must smoothly move over the surface without getting caught.

If the test probe gets caught, the respective area must be inspected with a magnifying

glass (8– to 10–fold magnification). If pitting (Figure 11, 12) or one single spalling is

detected, the transmission must not be used any longer. Transmissions with such a

finding must be removed and sent to the manufacturer.

D. Install drive stage:

(1) Replace O–ring (4, Figure 7) on drive stage.

(2) Install two guide bolts (1, Figure 15) on the transmission housing.

(3) Press back rollers in the pilot bearing (2, Figure 15). If necessary, use grease (CM101).

(4) Remove deposits from flange area on the main transmission.

(5) Using a hot air blower, heat transmission housing to a maximum of 60 degrees

centigrade.
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(6) Remove locking screws (6, Figure 7), washers (7) and nuts (8).

CAUTION PAY ATTENTION TO MARKINGS FOR THE INSTALLATION POSITION.

(7) Carefully insert drive stage into transmission housing and secure with a hexagon head

screw.

(8) Screw in the remaining hexagon head screws and torque–tighten crosswise to 8 to 10

Nm.

(9) Using the torque wrench, check again tightening torque of all screws.

(10) Replace O–ring on the oil nozzle (3, Figure 8). Insert oil nozzle and torque–tighten

screw to 4.5 to 5.5 Nm.

E. Install drive shaft i.a.w. AMM, 63-11-00, 4-1.

F. Perform ground run of engines for 5 minutes at power setting GROUND IDLE. To do so,

observe procedures and operational limits i.a.w. the model–related flight manual (FLM).

G. Accomplish a visual inspection of the main transmission in the area of the drive stages for

oil leakage.

Confirmation of accomplishment:

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

transmission:

Part 1: 

”Oil sample taken at xxx fh”.

Part 2: 

”Oil analysis evaluated at xxx fh, stage X determined, viscosity xx, water content xx”

Part 3:

”Chip detector indication noted at xxx fh, stage X”

Part 4:

”Toothing inspected at xxx fh” ”no damage / micropitting (gray staining)” or ”damage / pitting

/ rupture on tooth flank”

4. Appendix

If the transmission is removed, return the inspection report (page 28, 29) together with the note

of malfunction / reply form sheet (see also SI EC135-069).
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REVISION 05, 2011-09-06

Taking of the Oil Sample

Figure 1

1 Oil filler neck

2 Oil sample syringe

1

2
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ASB EC135-63A-010 accomplished:

Date:

Main transmission TT: Main transmission TSO:

SB EC135-63-011 accomplished:

Date:

Main transmission TT: Main transmission TSO:

Evaluation of the Oil Analysis

Figure 2

Fe

(ppm)

Oil (fh)

Fe

100 200 300 400 500 600

I

II

III

10

20

30

40

50

60

Type: EC135 EC635 P1 P2 P2+ T1 T2 T2+ CPDS CDS

Oil sample taken:

1)

2)

3)

4)

5)

6)

Date:

Main transmission TT:1) Main transmission

TSO:1)

Please make a copy of this page! The original of this page is to remain in the ASB!

Oil analysis for lubricating oil CM103 (MIL–PRF–23699)

Oil change 

(new oil)

Oil change

Fh oil: Water (%) Viscosity

1) at the last oil change

Fe (ppm)

Helicopter S/N:

Helicopter TT:

Main transmission S/N:

Customer:

Contact (Name): Phone: Fax: email

This form is also available on the internet: 

http://www.eurocoptersea.com ––> Download Center

Operator:

I Not critical, no measures required.

II measures i.a.w. stage II within 25 fh required.

III measures i.a.w. stage III within 10 fh required
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REVISION 05, 2011-09-06

ASB EC135-63A-010 accomplished:

Date:

Main transmission TT: Main transmission TSO

SB EC135-63-011 accomplished:

Date:

Main transmission TT: Main transmission TSO

Evaluation of the Oil Analysis

Figure 3

Oil sample taken:

1)

2)

3)

4)

5)

6)

Date:

Main transmission TT:1) Main transmission TSO:1)

Please make a copy of this page! The original of this page is to remain in the ASB!

Oil analysis for lubricating oil i.a.w. CM1001 (ZFNL–3001)

Fh oil: Water (%) Viscosity

1) at the last oil change

Fe (ppm)

Helicopter S/N:

Helicopter TT:

Main transmission S/N:

Customer:

Contact (Name): Phone: Fax: email

Fe

100 200 300 400 500 600

I

II

10

20

30

40

50

60

15

Oil change (new

oil) Oil change

70

III

80

85

45

Type: EC135 EC635 P1 P2 P2+ T1 T2 T2+ CPDS CDS

Operator:

This form is also available on the internet: 

http://www.eurocoptersea.com ––> Download Center

Fe

(ppm)

Oil (fh)

I Not critical, no measures required.

II measures i.a.w. stage II within 25 fh required.

III measures i.a.w. stage III within 10 fh required.
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ASB EC135-63A-010 accomplished:

Date:

Main transmission TT: Main transmission TSO

SB EC135-63-011 accomplished:

Date:

Main transmission TT: Main transmission TSO

I Not critical, no measures required.

II measures i.a.w. stage II within 25 fh required.

III measures i.a.w. stage III within 10 fh required

Oil sample taken:

Date:

Main transmission TT:1) Main transmission TSO:1)

Oil analysis for lubricating oil i.a.w. CM1001 (ZFNL–3001)

Fh oil: Water (%) Viscosity

1) at the last oil change

Fe (ppm)

Helicopter S/N:

Helicopter TT:

Main transmission S/N:

Customer:

Contact (Name): Phone: Fax: email

Type: EC135 EC635 P1 P2 P2+ T1 T2 T2+ CPDS CDS

Operator:

Measures i.a.w. 

stage II 

accomplished

Example of a Filled–Out Sheet for the Oil Analysis

Figure 4

Oil change 

(new oil) Oil change
ALERT SERVICE BULLETIN

EC135

EC135-63A-012

PAGE 17 of 29

2007-08-08

REVISION 05, 2011-09-06

Possible Deposits on Chip Detector

Figure 5

Stage A Stage B

Stage C Stage D
ALERT SERVICE BULLETIN

EC135

EC135-63A-012

PAGE 18 of 29 REVISION 05, 2011-09-06

2007-08-08

Installation of Chip Detector

Figure 6

1 Chip detector

2 Chip detector housing

1

2

View A

FLIGHT DIRECTION

10.2 – 13.8 Nm

(35–53 lb-in)

 Mark with safety lacquer (CM 680)
ALERT SERVICE BULLETIN

EC135

EC135-63A-012

PAGE 19 of 29

2007-08-08

REVISION 05, 2011-09-06

Drive Stage Components

Figure 7

1 Cover

2 Bearing

3 Shim

4 O–ring

5 Flange of free wheel shaft

6 screw

7 Washer

8 Nut

1 2

3

4

5 6 7 8

x2

x4 x2
ALERT SERVICE BULLETIN

EC135

EC135-63A-012

PAGE 20 of 29 REVISION 05, 2011-09-06

2007-08-08

Preparations for Drive Stage Removal

Figure 8

(4) Heat with hot

air blower

(3) Remove oil

nozzle

(1) Mark installation

position

(2) Mark with

LH or RH
ALERT SERVICE BULLETIN

EC135

EC135-63A-012

PAGE 21 of 29

2007-08-08

REVISION 05, 2011-09-06

Remove Drive Stage

Figure 9

(3) Remove drive stage

(1) Remove six of the seven

screws

(2) Leave uppermost hexagon head screw

tightened for securing purposes
ALERT SERVICE BULLETIN

EC135

EC135-63A-012

PAGE 22 of 29 REVISION 05, 2011-09-06

2007-08-08

Drive Pinion and Bevel Gear

Figure 10

(1) Components secured

to each other (2) Clean toothing

(2) Clean toothing

Bevel gear

Drive pinion
ALERT SERVICE BULLETIN

EC135

EC135-63A-012

PAGE 23 of 29

2007-08-08

REVISION 05, 2011-09-06

Visual Inspection of Toothing on Pinion

Figure 11

Tooth heel

Tooth toe

Tooth root

Admissible – no replacement necessary Not admissible – replacement necessary

Direction of view

Rotational

direction

Pitting Contact

pattern

Contact line Micro pitting / 

gray staining Spalling
ALERT SERVICE BULLETIN

EC135

EC135-63A-012

PAGE 24 of 29 REVISION 05, 2011-09-06

2007-08-08

Visual Inspection of Toothing on Bevel Gear

Figure 12

Tooth heel

Tooth toe

Tooth root

Admissible – no replacement necessary Not admissible – replacement necessary

Direction of

view

Pitting Contact

pattern

Contact line Micro pitting / 

gray staining Spalling
ALERT SERVICE BULLETIN

EC135

EC135-63A-012

PAGE 25 of 29

2007-08-08

REVISION 05, 2011-09-06

Drive Pinion and Bevel Gear

Figure 13

(4) Factory–applied silver lacquer

(3) Normal contact pattern

(2) Micropitting / gray staining

Pinion

Bevel gear

(5) Micropitting

(6) Normal contact pattern

(7) Factory–applied silver lacquer
ALERT SERVICE BULLETIN

EC135

EC135-63A-012

PAGE 26 of 29 REVISION 05, 2011-09-06

2007-08-08

Inspection of Teeth with Test probe

Bild 14

Pinion with micropitting and contact line

(1) In case of doubt, check contact line with Test

probe (2) and magnifying glass for micropitting

(3) Micropitting

(2) Test probe
ALERT SERVICE BULLETIN

EC135

EC135-63A-012

PAGE 27 of 29

2007-08-08

REVISION 05, 2011-09-06

Prepare Installation of Drive Stage

Figure 15

(2) Press back rollers of pilot

bearing

(1) Install guide bolt

approx. 80 mm

M6
ALERT SERVICE BULLETIN

EC135

EC135-63A-012

PAGE 28 of 29 REVISION 05, 2011-09-06

2007-08-08

Main transmission TT:1) Main transmission TSO:1)

Please make a copy of this page! The original of this page is to remain in the ASB!

Inspection report for the inspection i.a.w. Section 3, Part 4 (page 1 of 2)

––> Appendix to the note of malfunction / reply form sheet

1) at the last oil change

Helicopter S/N:

Helicopter TT:

Main transmission S/N:

Customer:

Contact (Name): Phone: Fax: email

Police Military EMS VIP civil Offshore Others

Africa Europe Far East Middle East South America North America Central America Others

Operator:

Main Transmission Part No: 4649 0___ ____ X

Main Transmission TSR: ______:____

Main transmission filled with oil Mil PRF 23699

Mobil Jet II AS500 AS555 AS560 BP2380 BP2389 Mobil256 Other

Main transmission filled with oil ZFNL3001 (TransmaxZ)

Reason for drive stage inspection:

SB EC135-63-011 ASB EC135-63A-012:

Oil change to ZFNL3001

(TransmaxZ) According to Section 3, Part 2 stage II

According to Section 3, Part 2 stage III

Chip Indication:

2x Stage A

1x Stage B

1x Stage C

1x Stage D

Name in block letters Date Signature

Type: EC135 EC635 P1 P2 P2+ T1 T2 T2+ CPDS CDS

This form is also available on the internet: 

http://www.eurocoptersea.com ––> Download Center

ASB EC135-63A-010 accomplished Date:

SB EC135-63-011 accomplished Date:

Main transmission TT:

Main transmission TT:
ALERT SERVICE BULLETIN

EC135

EC135-63A-012

PAGE 29 of 29

2007-08-08

REVISION 05, 2011-09-06

Inspection report for the inspection i.a.w. Section 3, Part 4 (page 2 of 2)

––> Appendix to the note of malfunction / reply form sheet

Helicopter S/N: Main transmission S/N:

Remarks:

Helicopter TT:

Finding result of LH drive stage:

Input Pinion: P/N 4649 302 041 Bevel Gear: P/N 4649 303 034

Serial No.: Serial No.:

Electronic pictures attached

No findings

Micro pitting / gray

staining

No findings

Micro pitting / gray

staining

Pitting

Rupture tooth flank

Pitting

Rupture tooth flank

Finding result of RH drive stage:

Input Pinion: P/N 4649 302 041 Bevel Gear: P/N 4649 303 034

Serial No.: Serial No.:

Electronic pictures attached

No findings

Micro pitting / gray

staining

No findings

Micro pitting / gray

staining

Pitting

Rupture tooth flank

Pitting

Rupture tooth flank

Result of Input Stage Inspection:

Main transmission remains in service Main transmission to be removed

Please make a copy of this page! The original of this page is to remain in the ASB!