MSB1 121

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Page 1 of 11 20 February 201 5 Replaces Issue: 05 February 201 5

1121

- 144_3 MSB, Inspection of starter solenoid 

# G 120A, A

- I

Grob Aircraft AG, Lettenbachstrasse 9, D

- 86874 Tussenhausen

- Mattsies 

# SERVICE BULLETIN NO. MSB1 121

- 1 44 / 3

I. TECHNICAL DETAILS

1.1 Category: Mandatory

Note: GROB issues Service Bulletins of category Mandatory (MSBs)

, if the information or

instructions have a safety intent either related to design or conformity and to publish revisions of manuals (AFM, AMM, IPC). However, a ccording to Article 20 (1) of Regulation (EC) No. 216/2008, o nly EASA may issue mandatory information, in the form of an Airworthiness Directive (AD), in order to react to a given safety problem. Service Bulletins classified Mandatory issued by GROB  ́s design organisation do not have a legally mandatory character equivalent to an AD, cannot have enforcement implications and, therefore, serve as information o r instruction by GROB only. This also applies to cases where a Service Bulletin is published in anticipation of an AD.

Note: This S ervice B ulletin is issued in anticipation of an AD. Issue of an AD will not

necessarily lead to revision of this S ervice B ulletin.

1.2 Airplanes affected:

G 120A all S/N

G 1 20A

- I all S/N

1.3 Time of Compliance:

Part A : Before next IFR or VFR Night flight , or within next 50FH , whichever comes first

, unless already accomplished under MSB 1121

- 144 at previous issue

. Part B : Within 100 flight hours

.

1.4 Subject:

ATA

- Code: 80

- 00 Starting Inspection of starter solenoid / Installation of a Starter Relay

1.5 Reason:

G ROB received a repo rt about a total loss of electrical power in IMC on a G 115E aircraft . Root

cause was found to be a defect starter solenoid. The starter solenoid had an internal defect causing a short circuit. The defect cannot be detected by visual inspection. The installation is

similar to the installation on G120 aircraft. Revision 3 of this Service Bulletin amends the impl ementation instructions

. This Service Bulletin is intended to prevent an unsafe condition. The configuration of the aircraft is affected by Part B of this Service Bulletin.

Note: Impleme ntation of MSB 1121

- 144/1, Part B prohibits application of RSB1121

- 128

.MSB1 121

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- 144_3 MSB, Inspection of starter solenoid 

# G 120A, A

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Grob Aircraft AG, Lettenbachstrasse 9, D

- 86874 Tussenhausen

- Mattsies 1.6 Concurrent documents: Corresponding AMM

1.7 Approval Note:

The technical content of this document is approved under the authority of EASA Design Organization Approval No. EASA.21J.030.

These information or instructions relate to change no. M ÄM 1121

- 189 which has been approved by the Authority (EASA) under approval no. 100 5 1942

.

1.8 Accomplishment/ Instructions

Part A One

- time Inspection

1.8.1 Disconnect the aircraft battery, refer to AMM Chapter 24

- 3 1

. 1.8.2 Remove the Engine Cowlings, r efer to AMM Chapter 71

- 10.

1.8.3 Visually i nspect the starter. Make sure that the power connection bolts have the same length, refer to Figure 1 for defective item and Figure 2 for correct installation

.

Figure 1 : Incorrect connection bolts Figure 2 : Correct installation

1.8.4 Release the two bolts on the starter solenoid . Carefully pull the solenoid away from the starter housing until the dead stop. Make sure that the solenoid plunger is still attached

, refer to Figure 3

. Attach the solenoid to the starter with the two bolts.MSB1 121

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- 144_3 MSB, Inspection of starter solenoid 

# G 120A, A

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Grob Aircraft AG, Lettenbachstrasse 9, D

- 86874 Tussenhausen

- Mattsies

Figure 3 : Starter solenoid at dead stop

1.8.5 If the starter is OK, do step 1.8.7

. 1.8.6 If the starter is not OK or in case of doubt , replace the Starter.

1.8.7 Install the Engine Cowlings; refer to AMM Chapter 71

- 10.

1.8.8 C onnect the aircraft battery; refer to AMM Chapter 24

- 3 1

. 1.8.9 Release aircraft into s ervice according to national requirements.

Part B /1 Installation of Starter Relay (Terminating action) with RSB1121

- 128

installed

1.8.10 Ensure that the aircraft is safe for parking I.A.W. AMM chapter 10

- 10.

1.8.11 Disconnect the aircraft battery for maintenance , refer to MM Chapter 24

- 3 0

. 1.8.12 Remove the Engine Cowlings, refer to MM Chapter 71

- 10.

1.8.13 D isconnect the spark plug cables from the spark plugs.



### 1.8.14 Unplug all terminals with cables from relay 5KA. Remove relay 5KA with clamp, bolt, two

washers and n ut from engine mount and discard.

Figure 4 : Relay 5KA

1.8.15 Unplug terminal with cables KA 02F20

- E and KA 09G20

- E from START BOOSTER 3KA connector VIN (red housing). Cut terminal as short as possible and discard it. Relay 5KAMSB1 121

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# G 120A, A

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Grob Aircraft AG, Lettenbachstrasse 9, D

- 86874 Tussenhausen

- Mattsies

Figure 5 : STARTER BOOSTER 3KA

1.8.16 Remove cable KA 09G20

- E ( previous routed from 5KA to 3KA) and Cable KA 07E14

- E (previous routed from 5KA to 2KA) and discard them

. 1.8.17 Drill a 5mm hole in the condenser frame 35m m left of the existing second hole of the top

condenser frame at the inner border

. Attach the new starter relay (7KA) (Item 1 of List

2.2 ), so that the terminals point downwards

. Use 2xM5 screw (Item 2 of List 2.2 ), 4xM5 washers (Item 3 of List 2.2 ) and 2xM5 nuts (Item 4 of List 2.2 ). To balance the distance between the condenser frame and the relay mounting bracket on the forward side, use an additional spacer (Item 5 of List 2.2 ).

Figure 6 : STARTER RELAY 7KA START BOOSTER

3KA

Spacer

New hole in condenser frame New starter relay 7KAMSB1 121

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Grob Aircraft AG, Lettenbachstrasse 9, D

- 86874 Tussenhausen

- Mattsies 1.8.18 Install and lengthen new cable KA 02H20

- E (Item 6 of List 2.2 ) , along existing cable loom from START BOOSTER 3KA to new starter relay 7KA with the pr e

- installed terminal at the starter relay 7KA end . Connect to terminal 86+ on relay 7KA.

1.8.19 On the START BOOSTER 3KA end d ismantle existing cables KA 02F20

- E and new

cable KA 02H20

- E, pair and crimp them to terminal AMP 160773

- 6 (Item 7 of List 2.2 ) by using crimping tool AMP 654174

- 1 or equivalent (Item 1 of List 2.3 )

. 1.8.20 Attach red housing AMP 154719

- 2 (Item 8 of List 2.2 ) to terminal and plug to S TART

B OOSTER 3KA connect ion VIN. Strap new cable to existing cable loom.

1.8.21 Use existing cable KA 08E20N

- P (previous located at 5KA) from VN17101 and root to

new starte r relay 7KA. Cut existing terminal as short as possible and discard it.

Dismantle cable KA 08E20N

- P and crimp to terminal MS25036

- 149 (Item 9 of List 2.2 ) by using crimping tool AMP 169400

- 0 or equivalent (Item 2 and 3 of List 2.3 )

. Connect to

terminal 85

- on relay 7KA.

1.8.22 Remove cable tie from rubber cap of middle bolt VV17103 on firewall. Push back cover to gain access to stop nut. Remove and discard nut and washer, therefore hold up counter nut and do not damage black wrapping tape. Remove cable complete KA

06E14

- E from VV17103 to relay 5KA and discard

. Remove cable PA 03G06

- E from bolt VV17103 (leave the rubber cap at the cable!) and route it back along existing wire to new starter relay 7KA. Connect to terminal 88a on starter relay 7KA. Secure rubber cap strap with cable tie (Item 10 of List 2.2 ).

1.8.23 Install new cable PA 03L06

- E (Item 11 of List 2.2 ) and connect to terminal 88 on starter relay 7KA t herefore the cable has to be led through the new rubber cap (Item 12 of List

2.2 ) . Root along existing loom to middl e bolt VV17103 on firewall. Therefore the cable has to be led through the new rubber cap (Item 12 of List 2.2 ). Tighten terminal with new washer and stop nut on bolt (Item 13 and 14 of List 2.2 ) , while holding up counter nut.

Paint with blue NYCOTE 7

- 11 protective coating (Item 15 of List 2.2 )

. 1.8.24 Let lacquer dry before reinstalling rubber cap . Sec ure rubber caps (on both end of

PA 03L06

- E) strap with cable tie (Item 10 of List 2.2 )

. 1.8.25 Install the jumper cable 115E

- 9510.03 (Item 16 of List 2.2 ) on the starter solenoid, refer to wiring diagram. Attach to connector “S” at Starter M otor 2KA using the old washer and

screw. Paint with blue NYCOTE 7

- 11 protective coating (Item 15 of List 2.2 ). Let lacquer dry before marking with inspection lacquer (Item 17 of List 2.2 ). ( See Figure 7 )

Figure 7 : STARTER 2KAMSB1 121

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# G 120A, A

- I

Grob Aircraft AG, Lettenbachstrasse 9, D

- 86874 Tussenhausen

- Mattsies 1.8.26 S ecure the cables with cable ties, where necessary.

1.8.27 C onnect the spark plug cables to the spark plugs

. 1.8.28 Install the Engine Cowlings, refer to AMM Chapter 71

- 10.

1.8.29 Connect the aircraft battery, refer to AMM Chapter 24

- 30.

1.8.30 Do an engine run

- up, refer to AMM Chapter 71

- 00.

1.8.31 Release aircraft into service according to national requirements.

Part B/2 Installation of Starter Relay (Terminating action) without RSB1121

- 128

installed

1.8.32 Ensure that the aircraft is safe for parking I.A.W. AMM chapter 10

- 10.

1.8.33 Disconnect the aircraft battery for maintenance , refer to MM Chapter 24

- 3 0

. 1.8.34 Remove the Engine Cowlings, refer to MM Chapter 71

- 10.

1.8.35 D isconnect the spark plug cables from the spark plugs.

1.8.36 Unplug terminal with cables KA 02G20

- E and KA 02F20

- E from Starter Booster 3KA connector VIN (red housing). Cut terminal as short as possible and discard it. Cap and

stow ca ble KA 02G20

- E with TC cap (Item 19 of List 2.2 ) using a heat gun (Item 4 of List

2.3 ).

Figu re 8 : STARTER BOOSTER 3KA

1.8.37 Drill a 5mm hole in the condenser frame 35mm left of the existing second hole of the top

condenser frame at the inner border

. Attach the new starter relay (7KA) (Item 1 of List

2.2 ), so that the terminals point downwards

. Use 2xM5 screw (Item 2 of List 2.2 ), 4xM5 washers (Item 3 of List 2.2 ) and 2xM5 nuts (Item 4 of List 2.2 ). To balance the distance between the condenser frame and the relay mounting bracket on the forward side, use an additional spacer (Item 5 of List 2.2 ). START BOOSTER

3KAMSB1 121

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- 144_3 MSB, Inspection of starter solenoid 

# G 120A, A

- I

Grob Aircraft AG, Lettenbachstrasse 9, D

- 86874 Tussenhausen

- Mattsies

Figure 9 : STARTER RELAY 7KA

1.8.38 Install and lengthen new cable KA 02H20

- E (Item 6 of List 2.2 ) , along existing cable loom from START BOOSTER 3KA to new starter relay 7KA with the preinstalled terminal at the starter relay 7KA end . Connect to terminal 86+ on relay 7KA.

1.8.39 On the START BOOSTER 3KA end dismantle existing cables KA 02F20

- E and new

cable KA 02H20

- E, pair and crimp them to terminal AMP 160773

- 6 (Item 7 of List 2.2 ) by using crimping tool AMP 654174

- 1 or equivalent (Item 1 of List 2.3 ) .Attach red housing

AMP 154719

- 2 (Item 8 of List 2.2 ) to terminal and plug to START BOOSTER 3KA connection VIN. Strap new cable to existing cable loom.

1.8.40 Remov e and discard nut and washer from grounding bolt VN 17101, therefore hold up counter nut. Remove terminal, turn by 180° and reattach to bolt. Install new cable KA

08E20N

- P (Item 20 of List 2.2 ) along existing cable loom from starter relay 7KA to grounding bolt VN 17101. Tighten terminal with new washer and stop nut on bolt (Item

21 and 22 of List 2.2 ) while ho lding up counter nut. Paint with blue NYCOTE 7

- 11 protective coating (Item 15 of List 2.2 ). Strap in new cable back in cable loom strap with cable ties. (See Figure 10 ) New starter relay 7KA

Spacer New hole in condenser frameMSB1 121

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Grob Aircraft AG, Lettenbachstrasse 9, D

- 86874 Tussenhausen

- Mattsies Figure 10 Bolts at Firewall

1.8.41 Remove cable tie from rubber cap of middle bolt VV17103 on firewall. Push back cover to gain access to stop nut. Remove and discard nut and washer, therefore hold up counter nut and do not damage black wrapping tape. Remove cable KA 06E14

- E complete from VV17103 to relay 5KA and discard

. Remove cable PA 03G06

- E from bolt VV17103 (leave the rubber cap at the cable!) and route it back along existing wire to new starter relay 7KA. Connect to terminal 88a on starter relay 7KA. Secure rubber cap strap with cable tie (Item 10 of List 2.2 ).

1.8.42 Install new cable PA 03L06

- E (Item 11 of List 2.2 ) and connect to terminal 88 on starter relay 7KA t herefore the cable has to be led through the new rubber cap (Item 12 of List

2.2 ) . Root along existing loom to middl e bolt VV17103 on firewall. Therefore the cable has to be led through the new rubber cap (Item 12 of List 2.2 ). Tighten terminal with new washer and stop nut on bolt (Item 13 and 14 of List 2.2 ) , while holding up counter nut.

Paint with blue NYCOTE 7

- 11 protective coating (Item 15 of List 2.2 ).

1.8.43 Let lacquer dry before reinstalling rubber cap . Sec ure rubber caps (on both end of

PA 03L06

- E) strap with cable tie (Item 10 of List 2.2 )

. 1.8.44 Unplug terminal with cable KA 02G20

- E from Engine Starter Motor 2KA connector “S”. Keep screw and washer. Cut terminal as short as possible and discard it. Cap and stow

cable KA 02G20

- E wit h TC cap (Item 19 of List 2.2 ) using a heat gun (Item 4 of List 2.3 ).

1.8.45 Install the jumper cable 115E

- 9510.03 (Item 16 of List 2.2 ) on the starter solenoid, refer to wiring diagram. Attach to connector “S” at Starter Motor 2KA using the old washer and

screw. Paint with blue NYCOTE 7

- 11 protective coating (Item 15 of List 2.2 ). Let lacquer dry before marking with inspection lacquer (Item 17 of List 2.2 ). (See Figure 11 ) VN 17101 Grounding Bolt VV 17103MSB1 121

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- 144_3 MSB, Inspection of starter solenoid 

# G 120A, A

- I

Grob Aircraft AG, Lettenbachstrasse 9, D

- 86874 Tussenhausen

- Mattsies Figure 11 : STARTER 2KA

1.8.46 Safety the cables with cable ties, where necessary.

1.8.47 C onnect the spark plug cables to the spark plugs

. 1.8.48 Install the Engine Cowlings, refer to AMM Chapter 71

- 10.

1.8.49 Connect the aircraft battery, refer to AMM Chapter 24

- 30.

1.8.50 Do an engine run

- up, refer to AMM Chapter 71

- 00.

1.8.51 Release aircraft into service according to national requirements.

1.9 Repetitive Actions

noneMSB1 121

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Grob Aircraft AG, Lettenbachstrasse 9, D

- 86874 Tussenhausen

- Mattsies



## II. PLANNING INFORMATION

2.1 Weight and CG

N/A

2.2 Material and Availability

Part B /1 :

Item P/N Description Qty. / A/C

1 GS246001

- 9 Starter Relay 1

2 LN9037

- 05018 Screw 2

3 LN9025

- 0510 Washers 4

4 LN9348

- 05 Nut 2

5 NAS43DD3

- 6N Spacer 1

6 120A

- 940010.02A KA 02H20

- E 1

7 AMP 160773

- 6 Terminal 1

8 AMP 154719

- 2 H ousing , Red 1

9 MS25036

- 149 Terminal, Red 1

10 GS510010

- 100 Cable Ty, B lue 8

11 115E

- 9470.01 PA 03 L 06

- E 1

12 MS 25171

- 3S Rubber Caps 2

13 LN9348

- M8 Nut 1

14 LN 9025

- 0815L Washer 1

15 Nycote7

- 11 BLUE Protective Coating AR

to be ordered separately

16 115E

- 9510.03 Jumper cable 1

17 GS513010 Inspection Lacquer AR

to be ordered separately

18 GS510010

- 200 Cable Ty, B lue 4

Part B/2 : additional

19 GS247009

- 2

- 32 H eatshrinkable C aps 2

20 1 20A

- 940010.01A KA 0 8E20N

- P 1

21 LN9348

- M10 Nut 1

22 LN 9025

- 1020L Washer 1MSB1 121

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Grob Aircraft AG, Lettenbachstrasse 9, D

- 86874 Tussenhausen

- Mattsies 2.3 Special Tools

Part B /1 :

Item P/N Description

1 AMP 654174

- 1 (or equivalent) Crimping tool PEZ 100

2 AMP 169400

- 0 (or equivalent) Crimping tool CERTI

- LOK

3 AMP 16940 4 (or equivalent) Die Set for AMP 169400

- 0

Part B/2 : additional

4 Commercial Heat Gun

2.4 Labor costs

N/A

2.5 Reference documents Corresponding AMM and IPC

2.6 Credit

N/A



## III. REMARKS

The instructions in paragraph 1.8 have to be accomplished and certified in the logbook by

authorized staff:

- in EASA countries according to Article 5 VO EG 2042/03 (VO EG 1056/2008) Appendix III

– Part 66

- in non

- EASA countries according to national regulations with respect to maintenance.

If you have sold your aircraft in the meantime, we kindly ask you to forward this informat ion to the new owner and to provide us with the name and address of the new owner as well as with the respective serial number.

For questions and assistance please contact:

Product Support, phone: +49 8268 9981 05

fax: +49 8268 998200

e

- mail: productsupport@grob

- aircraft.com