MSB1078-186/2 

Page 1 of 6 

28 March 2012 

Replaces Issue: 08. Mar 2012

1078-186_2 MSB, Inspection of elevator trim tab arm Rev.2 G 115E/EG 

Grob Aircraft AG, Lettenbachstrasse 9, D-86874 Tussenhausen-Mattsies 

SERVICE BULLETIN NO. MSB1078-186/2 

I. TECHNICAL DETAILS

1.1 Category:

Mandatory 

1.2 Airplanes affected:

G 115E all S/N 

G 115EG all S/N 

1.3 Time of Compliance:

Part A: Next 50 hours inspection or next regular inspection whichever comes first, before receipt 

of material for terminating action. 

Note: Replacement of an affected trim tab arm in accordance with the instructions of 

MSB 1078-186 at original issue is acceptable to comply with Part A of this Service 

Bulletin. 

Accomplishment of MSB 1078-186/1 is acceptable to comply with Part A of this 

Service Bulletin. 

Part B: Terminating action: Next 50 hours inspection or next regular inspection whichever 

comes first, after receipt of material. 

1.4 Subject:

ATA-Code: 55-20 Elevators and Trim tab 

 Inspection of elevator trim tab arm 

1.5 Reason:

Grob received a report from a fleet operator that an elevator trim tab arm P/N 115E-3758 was 

found cracked from a rear mounting hole (either L/H or R/H) to the rear edge of the trim tab arm. 
MSB1078-186/2 

Page 2 of 6 

28 March 2012 

Replaces Issue: 08. Mar 2012

1078-186_2 MSB, Inspection of elevator trim tab arm Rev.2 G 115E/EG 

Grob Aircraft AG, Lettenbachstrasse 9, D-86874 Tussenhausen-Mattsies 

Fig. 1 

Dye penetrant check of defective items revealed, that a visual inspection of an installed item 

mandated with MSB1078-186 at original issue may not be sufficient to detect every crack on the 

bracket (Fig. 2). 

Fig. 2 

Therefore a dye penetrant check or more significant NDT of the dismounted parts has been 

mandated by MSB1078-186/1 to ensure safe operation until the terminating action will be

accomplished. 

Investigation of defective parts revealed corrosion cracking as cause for cracks. To prevent 

future cracking, the Trim Tab Arm 115E-3758 is replaced by 115E-3758/1, which is 

manufactured from an alloy resistant to corrosion cracking. In addition to that, shaping is 

improved and a paint coat is applied.

1.6 Concurrent documents:

G 115E: AMM TR No. 05-21 

G 115EG: AMM / JG TR No. 05SMC-03, 05SMC-04, 05GV-04 

Location of crack
MSB1078-186/2 

Page 3 of 6 

28 March 2012 

Replaces Issue: 08. Mar 2012

1078-186_2 MSB, Inspection of elevator trim tab arm Rev.2 G 115E/EG 

Grob Aircraft AG, Lettenbachstrasse 9, D-86874 Tussenhausen-Mattsies 

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. MÄM1078-161 which has been approved 

under the authority of EASA Design Organisation Approval No. EASA.21J.030.

1.8 Accomplishment/ Instructions

Part A 

1.8.1 Ensure that the aircraft is safe for parking I.A.W. G 115E AMM chapter 10-10 and G 115EG 

Job Guide in analogy. 

1.8.2 Inspect elevator trim tab operating arm for signs of cracking, especially both upper and 

lower surfaces from the rear bolt mounting holes to the rear of the operating arm. 

1.8.3 Remove trim tab I.A.W. G 115E AMM chapter 55-20 para. 3B and G 115EG Job Guide 

in analogy 

1.8.4 Remove trim tab arm (item 10 in Fig. 3) by removing nut, washer and bolt (item 20, 30, 

40 in Fig. 3) 

10 

20

30

40

Left Elevator

Fig. 3 

1.8.5 Perform dye penetrant check or more significant NDT on trim tab arm P/N 115E-3758 

1.8.6 If no crack is found, clean trim tab bracket and proceed with 1.8.8 
MSB1078-186/2 

Page 4 of 6 

28 March 2012 

Replaces Issue: 08. Mar 2012

1078-186_2 MSB, Inspection of elevator trim tab arm Rev.2 G 115E/EG 

Grob Aircraft AG, Lettenbachstrasse 9, D-86874 Tussenhausen-Mattsies 

1.8.7 If a crack is confirmed, the trim tab arm has to be replaced by a new item. 

Note: Any finding has to be reported to Grob with aircraft S/N and flight hours. 

1.8.8 Install trim tab arm P/N 115E-3758 using bolt, washer and new locking nut (item 20, 30, 

40 in Fig. 3). Apply correct torque value I.A.W. G 115E AMM chapter 20-10 and 

G 115EG Job Guide in analogy. 

Note: In place of installing the original trim tab arm according 1.8.8, you may proceed with 

1.8.14 of Part B following receipt of new material.

1.8.9 Install trim tab I.A.W. G 115E AMM chapter 55-20 para. 3C and G 115EG Job Guide in 

analogy 

Note: Make sure, that the bolt holes of trim rods 3 are in alignment with the trim arm and the 

bolts may be installed easily. If necessary adjust accordingly I.A.W. G 115E AMM chapter 

27-31 para. B and G 115EG Job Guide in analogy. 

1.8.10 Return aircraft to service as per relevant procedures and regulations. 

Part B Terminating Action 

1.8.11 Ensure that the aircraft is safe for parking I.A.W. G 115E AMM chapter 10-10 and 

G 115EG Job Guide in analogy. 

1.8.12 Remove trim tab I.A.W. G 115E AMM chapter 55-20 para. 3B and G 115EG Job Guide 

in analogy 

1.8.13 Remove trim tab arm (item 10 in Fig. 3) by removing nut, washer and bolt (item 20, 30, 

40 in Fig. 3) 

1.8.14 Install new trim tab arm P/N 115E-3758/1 (item 4 of List 2.2) using bolt, washer and new 

locking nut (item 20, 30, 40 in Fig. 3). Apply correct torque value I.A.W. G 115E AMM 

chapter 20-10 and G 115EG Job Guide in analogy. 

1.8.15 Install trim tab I.A.W. G 115E AMM chapter 55-20 para. 3C and G 115EG Job Guide in 

analogy 

Note: Make sure, that the bolt holes of trim rods 3 are in alignment with the trim arm and the 

bolts may be installed easily. If necessary adjust accordingly I.A.W. G 115E AMM chapter 

27-31 para. B and G 115EG Job Guide in analogy. 

1.8.16 Return aircraft to service as per relevant procedures and regulations. 
MSB1078-186/2 

Page 5 of 6 

28 March 2012 

Replaces Issue: 08. Mar 2012

1078-186_2 MSB, Inspection of elevator trim tab arm Rev.2 G 115E/EG 

Grob Aircraft AG, Lettenbachstrasse 9, D-86874 Tussenhausen-Mattsies 

1.9 Repetitive Actions

Repeat special inspection in para 1.8 Part A every 200FH until the terminating action Part B is 

accomplished. 

For regular inspection refer to G 115E AMM, Chap. 05-20, para. 10 and G 115EG Job Guide in 

analogy. 

II. PLANNING INFORMATION

2.1 Weight and CG

N/A 

2.2 Material and Availability

Item P/N Description Qty. / A/C 

1 115E-3758 Trim Tab Arm (pre-modification) 1 

2 LN9348-05 Lock Nut 4 

3 LN9348-06 Lock Nut 1 

4 115E-3758/1 Trim Tab Arm (post modification) 1 

2.3 Special Tools

N/A 

2.4 Labor costs

N/A 

2.5 Reference documents

Corresponding AMM and IPC 

2.6 Credit

N/A 
MSB1078-186/2 

Page 6 of 6 

28 March 2012 

Replaces Issue: 08. Mar 2012

1078-186_2 MSB, Inspection of elevator trim tab arm Rev.2 G 115E/EG 

Grob Aircraft AG, Lettenbachstrasse 9, D-86874 Tussenhausen-Mattsies 

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 information 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: 

 Rudi Vodermeier, Head of Customer Service & Support, 

phone: +49 8268 998139 

 fax: +49 8268 998200 

 e-mail: productsupport@grob-aircraft.de

SB-Index: http://www.grob-aircraft.eu/service-and-support/g-115.html

Order: http://www.grob-aircraft.eu/service-and-support/general/order-form.html