SERVICE BULLETIN

ORIGINAL ISSUE: Jul 31/12 57-JA120141 

REVISION 1: Apr 08/14 PAGE 1 OF 1 

SERVICE BULLETIN

BAE SYSTEMS (OPERATIONS) LIMITED, 

PRESTWICK INTERNATIONAL AIRPORT, 

AYRSHIRE, KA9 2RW, 

SCOTLAND. 

57-JA120141 

TRANSMITTAL SHEET 

This page transmits the Revision 1 to Inspection Service Bulletin 57-JA120141. 

TITLE: INSPECTION OF MAIN LANDING GEAR TRUNNION CAP TENSION BOLTS 

INSPECTION SERVICE BULLETIN 

REASON FOR REVISION 

Inspection Service Bulletin is revised to clarify accomplishment instructions of the Main Landing 

Gear Trunnion Cap Tension Bolts and parts list. 

INSTRUCTIONS FOR INCORPORATION 

Remove and discard entire bulletin pages 1 through 12 at Initial Issue. 

Add new pages 1 through 12 complete at Revision 1. 

ORIGINAL ISSUE: Jul 31/12 57-JA120141 

REVISION 1: Apr 08/14 PAGE 1 OF 12 

SERVICE BULLETIN

BAE SYSTEMS (OPERATIONS) LIMITED, 

PRESTWICK INTERNATIONAL AIRPORT, 

AYRSHIRE, KA9 2RW, 

SCOTLAND. 

TITLE: INSPECTION OF MAIN LANDING GEAR TRUNNION CAP TENSION BOLTS 

INSPECTION SERVICE BULLETIN 

1. PLANNING INFORMATION 

A. Effectivity 

Jetstream Series 3100 and Series 3200 aircraft. 

B. Reason 

For aircraft pre-mod JM5218 the Trunnion Cap Tension Lower Bolts MS21250 will have 

geometric interference between the bolt underhead radius and trunnion cap hole. This 

could lead to cracking and failure of the bolt. 

For aircraft post-mod JM5218, in the Illustrated Parts Catalogue (IPC), there is an option to 

install either 12 point double hex head MS21250 bolts or aircraft spline drive head 

MS21134 bolts to retain the MLG Trunnion Caps. 

Both types of bolt have a radius under the head to the shank. The IPC identifies that a 

countersunk washer is to be used under the head of MS21250 bolts. However, the 

requirement to fit a countersunk washer under the head of MS21134 has been omitted from 

the Aircraft Maintenance Manual. 

There will be geometric interference between the bolt underhead radius and trunnion cap 

hole if a countersunk washer is not installed. This could lead to cracking and failure of the 

bolt, which could compromise the structural integrity of the other tension bolts holding the 

main landing gear in place, resulting in collapse of the main landing gear. 

C. Description 

The work covered by this Service Bulletin affects the left and right main landing gear. 

The tasks are as follows: 

Pre-Mod JM5218 

- Make the aircraft safe for servicing. 

- Gain access to main landing gear Trunnion Cap Tension Bolts. 

- Identify and remove bolt(s). 

- Inspect bolt(s) using Magnetic Particle Inspection (MPI), to confirm cracks are not 

present. 

57-JA120141 
SERVICE BULLETIN

57-JA120141 ORIGINAL ISSUE: Jul 31/12 

PAGE 2 REVISION 1: Apr 08/14 

- Re-install crack-free or replacement bolts, with countersunk washers under each bolt 

head. 

- Close up. 

- The aircraft records are amended. 

Post-Mod JM5218 

- Make the aircraft safe for servicing. 

- Gain access to main landing gear Trunnion Cap Tension Bolts. 

- Visually inspect the Trunnion Cap Bolts to determine which type of bolt (head) is 

installed and washer is installed under each bolt head. 

- If 12 point double-hex head (MS21250) bolts and washers are installed, no further action 

is required at this time. 

- If any spline head (MS21134) bolts are found installed, remove bolts. 

- If washers are not installed, remove bolts. 

- If bolts are being re-installed, inspect bolt(s) using Magnetic Particle Inspection (MPI), to 

confirm cracks are not present. 

- Re-install crack-free or replacement bolts, with washers under each bolt head. 

- Close up. 

- The aircraft records are amended. 

D. Manpower 

2 man-hours for inspection, (Mechanical skills are necessary). 

4 man-hours for removal and installation of bolts and washers, (Mechanical and NDT skills 

are necessary). 

E. Material - Cost and Availability 

For the terms and conditions for the supply of material, Operators are to contact: 

Jetstream Support, 

Saywell International, 

Aviation Centre, 

Downlands Business Park, 

Worthing, 

West Sussex, 

BN14 9LA, UK. 

Main: +44(0) 1903 704900 

Fax: +44(0) 1903 705761 

Email: jetstream@saywell.co.uk

F. Tooling - Price and Availability 

Cost and availability is by arrangement between the Operator and BAE SYSTEMS. 
SERVICE BULLETIN

ORIGINAL ISSUE: Jul 31/12 57-JA120141 

REVISION 1: Apr 08/14 PAGE 3 

G. Weight and Balance 

None. 

H. Aircraft Noise Levels 

Not affected. 

I. Electrical Load Data 

Not affected. 

J. Software Accomplishment Summary 

Not applicable. 

K. References 

- Aircraft Maintenance Manual. 

- Illustrated Parts Catalogue. 

- Non-Destructive Inspection Manual. 

L. Publications Affected 

- Aircraft Maintenance Manual. 

- Illustrated Parts Catalogue. 

Operators are requested to advise the Business Support Team, Technical Publications, 

BAE SYSTEMS (Operations) Limited, Prestwick International Airport, Ayrshire, KA9 2RW, 

SCOTLAND. of the accomplishment of this service bulletin and request the necessary 

revisions for the affected manuals. 

M. Family Tree Of Modification Relationships 

Not applicable. 
SERVICE BULLETIN

57-JA120141 ORIGINAL ISSUE: Jul 31/12 

PAGE 4 REVISION 1: Apr 08/14 

N. Approval 

This Service Bulletin must be accomplished within 500 landings from the original issue 

date. 

Any bolt that is found to be cracked must be replaced before further flight. 

If a bolt is not available to replace an existing bolt that is too short to be installed with a 

countersunk washer under the head, then the existing bolt may be re-installed without a 

washer, subject to a 500 landing repeat MPI for up to 2000 landings, after which it must be 

replaced with a longer bolt and countersunk washer.

The technical content of this Service Bulletin is be the subject of EASA Airworthiness 

Directive consultation. 

The technical content of this Service Bulletin is approved under the authority of EASA 

PART 21 Approval No. EASA.21J.047. 
SERVICE BULLETIN

ORIGINAL ISSUE: Jul 31/12 57-JA120141 

REVISION 1: Apr 08/14 PAGE 5 

2. ACCOMPLISHMENT INSTRUCTIONS 

WARNING: MAKE SURE THE AIRCRAFT AND THE AIRCRAFT SYSTEMS ARE MADE SAFE 

AS DETAILED IN THE APPLICABLE CHAPTERS OF THE AIRCRAFT 

MAINTENANCE MANUAL. 

NOTE: Abbreviations used in the accomplishment instructions of this service bulletin are: 

 AMM - Aircraft Maintenance Manual. 

 NDI - Non-Destructive Inspection Manual. 

A. Preparation 

(1) Refer to AMM Chapter 24. Remove electrical power from the aircraft and display 

“POWER OFF” notices. 

(2) Place a warning placard in the flight compartment to prevent operation of the landing 

gear. 

(3) If the need to replace any bolt is identified raise aircraft on jacks as detailed in AMM 

Chapter 7. 

B. Accomplishment 

For aircraft Pre-Mod JM5218 

(1) Refer to Figures 1 and 2, identify the Trunnion Cap Tension Bolts. 

(2) Remove bolts MS21250 i.a.w. AMM 32-10-11 – only one bolt per side affected. 

(3) Inspect bolts using Magnetic Particle Inspection i.a.w. NDI Part 5, 20-05-01, to 

confirm cracks are not present. 

(4) Re-install crack-free or replacement bolts together with countersunk washers i.a.w. 

AMM 32-10-11. For 3/8 in. dia. bolts washer PKS1000-6-2-S are to be used. For 

7/16 in. dia. Bolts, washer PKS1000-7-2-S are to be used. 

For aircraft Post-Mod JM5218 

(1) Refer to Figures 1 and 2, visually inspect the Trunnion Cap Tension Bolts to 

determine which type of bolt is installed. 

(2) If 12 point double-hex head MS21250 bolts are installed and countersunk washers 

are evident under each bolt head, no further action is required at this time. 

(3) If any bolts are to be removed, then they should be removed and replaced one at a 

time, (i.e. at least 3 bolts should be installed at all times). 

(4) If any spline head MS21134 bolts are found installed, or MS21250 bolts are installed 

without countersunk washers, remove bolts i.a.w. AMM 32-10-11. 

(a) Refer to Figure 1 and paragraph 3.B. If the existing bolts are spline head 

MS21134, these must be removed and discarded. The existing MS21134 parts 

are not long enough to allow countersunk washers to be fitted. As replacements 
SERVICE BULLETIN

57-JA120141 ORIGINAL ISSUE: Jul 31/12 

PAGE 6 REVISION 1: Apr 08/14 

to be installed, MS21250 or (longer) MS21134 are new bolts, Magnetic Particle 

Inspection is not required. 

NOTE: If a bolt is not available to replace an existing bolt that is too short to be installed with a 

countersunk washer under the head, then the existing bolt me be re-installed without a 

washer, subject to a 500 landing repeat MPI for up to 2000 landings, after which it must 

be replaced with a longer bolt and countersunk washer. 

(b) If the existing bolts are 12 point double-hex head MS21250 and these bolts are 

to be re-installed, inspect bolt(s) using Magnetic Particle Inspection i.a.w. NDI 

Part 5, 20-05-01, to confirm cracks are not present. 

(5) Re-install crack-free or replacement bolts and countersunk washers iaw AMM 32-

10-11. 

C. Recovery 

(1) Remove the warning placard placed in the flight compartment to prevent operation 

of the landing gear while the inspections were done. 

(2) Refer to AMM Chapter 24. Restore electrical power to the aircraft and remove 

“POWER OFF” notices. 

(3) Refer to AMM Chapter 7. Lower the aircraft off the jacks if required. 

(4) Add Service Bulletin number ‘32-JA120141’ to the aircraft records. 

NOTE: Operators are reminded of the necessity to inform the Business Support Team, 

Technical Publications, BAE SYSTEMS (Operations) Limited, Prestwick International 

Airport, Ayrshire, KA9 2RW, SCOTLAND. of the accomplishment of this service bulletin 

in order to obtain the necessary revisions for the affected manuals, see paragraph 1.L. 

Publications Affected, of this bulletin. 
SERVICE BULLETIN

ORIGINAL ISSUE: Jul 31/12 57-JA120141 

REVISION 1: Apr 08/14 PAGE 7 

MAIN LANDING GEAR TRUNNION CAP BOLTS 

FIGURE 1 
SERVICE BULLETIN

57-JA120141 ORIGINAL ISSUE: Jul 31/12 

PAGE 8 REVISION 1: Apr 08/14 

ACCOMPLISHMENT FLOW CHART 

FIGURE 2 
SERVICE BULLETIN

ORIGINAL ISSUE: Jul 31/12 57-JA120141 

REVISION 1: Apr 08/14 PAGE 9 

3. MATERIAL INFORMATION 

A. New parts supplied as a material kit 

None. 

B. Replacement Parts - Operators Supply 

Old Part No. New Part No. QTY Keyword 

Post-mod JM5218 

 

MS21134H07045 

or 

MS21250H07046 

MS21250H07046 

or 

MS21134H07046 

A/R MLG Trunion Cap Tension Bolt 

 

MS21134H07059 

or 

MS21250H07060 

MS21250H07060 

or 

MS21134H07060 

A/R MLG Trunion Cap Tension Bolt 

 

PKS1000-7-2-S A/R Countersunk Washer for 7/16 in. dia. Bolts 

 

For Pre-mod JM5218 

MS21250H06040 MS21250H06040 A/R MLG Trunion Cap Tension Bolt 

PKS1000-6-2-S 2 Countersunk Washer for 3/8 in. dia. Bolts 

or 

MS21250H07040 MS21250H07040 A/R MLG Trunion Cap Tension Bolt 

PKS1000-7-2-S 2 Countersunk Washer for 7/16 in. dia. Bolts 

C. Instruction Dispositions Notes 

None. 
SERVICE BULLETIN

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PAGE 10 REVISION 1: Apr 08/14 

BLANK PAGE 
SERVICE BULLETIN

ORIGINAL ISSUE: Jul 31/12 57-JA120141 

REVISION 1: Apr 08/14 PAGE 11 

4. CONTINUED AIRWORTHINESS 

A. Continued Airworthiness Instructions 

There are no continued airworthiness instructions applicable to this service bulletin. 

B. Scheduled Maintenance 

(1) Not applicable. 

C. Removal Procedures 

(1) Not applicable. 

D. Installation Procedures 

(1) Not applicable. 

E. Test Procedures 

(1) Not applicable. 

F. Trouble Shooting 

(1) Not applicable. 
SERVICE BULLETIN

57-JA120141 ORIGINAL ISSUE: Jul 31/12 

PAGE 12 REVISION 1: Apr 08/14 

BLANK PAGE 
ACCOMPLISHMENT REPORT 

SERVICE BULLETIN NUMBER 57-JA120141 

TITLE: INSPECTION OF MAIN LANDING GEAR TRUNNION CAP TENSION BOLTS

TO: BUSINESS SUPPORT TEAM, 

 TECHNICAL PUBLICATIONS, 

 BAE SYSTEMS (OPERATIONS) LIMITED, 

 PRESTWICK INTERNATIONAL AIRPORT, 

 AYRSHIRE, KA9 2RW, 

 SCOTLAND. 

 Telephone: (01292) 675207 

 Fax: (01292) 675704 

 E-mail: RAPublications@baesystems.com 

PLEASE BE ADVISED THAT THE ABOVE SERVICE BULLETIN HAS BEEN EMBODIED ON 

AIRCRAFT CONSTRUCTORS NUMBER(S): 

WE REQUEST THE APPROPRIATE REVISIONS TO APPLICABLE MANUALS. 

NAME: .................................................................................. 

SIGNED: ............................................................................... 

COMPANY: .......................................................................... 

DATE: .................................................................................. 

SERVICE BULLETIN COMMENTS/FEEDBACK 

Please report any non-technical comments or inaccuracies regarding this service bulletin to the 

above address.