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# SERVICE BULLETIN BAE SYSTEMS (OPERATIONS) LIMITED, PRESTWICK INTERNATIONAL AIRPORT, AYRSHIRE, KA9 2RW, SCOTLAND. J41-24-043

TRANSMITTAL SHEET This page transmits revision 3 of service bulletin J41-24-043, pages 1 to 20. TITLE: ELECTRICAL POWER - DC GENERATION - OVERHEAT FAILURE OF EARTH POSTS (LEFT AND RIGHT}. INSPECTION Actions (1) Remove and discard service bulletin at revision 2. (2) Insert Service Bulletin at revision 3. Reasons for Revision (1) Para.2 .B.(2)
.(e) Accomplishment- Torque value changed to 200 lbf.in. (22
.6 Nm .) (2) Para.2.C.(1). Recovery - Installation of fairings added. INCORPORATION OF THIS REVISION DOES NOT REQUIRE REWORK OF THE MODIFICATION(S) EMBODIED BY EARLIER REV ISIONS OF THIS SERVICE BULLETIN.

ORIGINAL ISSUE: SEP 27/11 Revision 3: 1 61 h June 20 14 J41-24-043 PAGE 1 OF 1

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# SERVICE BULLETIN BAE SYSTEMS (OPERATIONS) LIMITED, PRESTWICK INTERNATIONAL AIRPORT, AYRSHIRE, KA9 2RW, SCOTLAND. J41-24-043 TITLE: ELECTRICAL POWER- DC GENERATION- OVERHEAT FAILURE OF EARTH POSTS (LEFT AND RIGHT). INSPECTION BULLETIN 1. PLANNING INFORMATION A. Effectivity All Jetstream Series 41 00 Aircraft. B. Reason An operator has reported an incident involving an overheat failure of the bracket on which is located the earth post for the generator and propeller de-ice systems. Although the earth post and cables were not damaged, the mounting bracket and underlying structure was damaged and needed to be replaced or repaired. This Service Bulletin is to make sure there are no signs of corrosion or damage to the aircraft structure on or around the bracket, that the earth posts are secure and that the electrical performance of each earth post is within specified limits. C. Description This Service Bulletin calls for an inspection of the earth post EP2 (Left) and earth post EP4 (Right) on the structure for the Left and Right power plants. The tasks are as follows:

- Fairing panels are removed.

- Inspect for signs of arcing and lateral movement of the earth post.

- A high-current millivolts-drop test is done between each earth post and the main wing

structure.

- The panels are installed.

- The aircraft records are amended
. D. Manpower 4.0 man-hours. Electrical skills are necessary.
ORIGINAL ISSUE: SEP 27/11 Revision 3: 161 h June 2014 J41-24-043 PAGE 1 of 20

### 8AeJETSTREA.M SBn•s 4ffJIJ SERVICE BULLETIN E. Material -Cost and Availability Not applicable. F. Tooling- Price and Availability Refer to AMM Subtask 20-21-00-760-004.

ITEM 20-0002 Ammeter, 150 amp. ITEM 20-0007 Millivolt meter. ITEM 20-0009 Variable power-supply unit, 150 amp. Alternatively, use the following commercially available equipment or equivalent.

Megger MOM2 High current hand held micro-ohmmeter. G. Weight and Balance None. H. Aircraft Noise Levels Aircraft noise is not affected. I. Electrical Load Data Not affected. J. Software Accomplishment Summary Not applicable
. 

### K. References

- Aircraft Maintenance Manual (AMM). Chapters 06, 12, 20 and 71.

- Structural Repair Manual (SRM). Chapter 51. L. Publications Affected

J41-24-043 PAGE2 None.

ORIGINAL ISSUE: SEP 27/11 Revision 3: 161 h June 2014

### 8Ae JETST.REAIII StlnBS4"){} SERVICE BULLETIN M. Family Tree Of Modification Relationships Not applicable. N. Approval BAE SYSTEMS recommends that this service bulletin is accomplished within 12 months of the original issue date of this service bulletin. The technical content of this service bulletin is 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.
Signed Date EASA Part 21 Approval No. EASA.21J.047.

ORIGINAL ISSUE : SEP 27/11 Revision 3: 161 h June 2014 J41-24-043 PAGE 3J41-24-043 PAGE4 

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ORIGINAL ISSUE: SEP 27/11 Revision 3: 161 h June 2014

## IAeJETSTREAM &ttuN164,()() SERVICE BULLETIN 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. SRM - Structural Repair Manual. A. Preparation (1) Refer to AMM, Chapter 12-00-00. Remove all aircraft electrical power. (2) Display a warning notice in the flight compartment 'DO NOT APPLY POWER TO THE AIRCRAFT'
. B. Accomplishment - Left and Right - Information in brackets is applicable to the Right installation
. (1) Refer to the AMM Chapters 06 and 71. Remove the inboard fairing panel 414AR from the left engine and the outboard fairing panel 424AR from the right engine. (2) Refer to Figu re 1 and the SRM Chapter 51. Look for defects and take actions as follows : (a) Inspect the structure around the earth post EP2 (EP4) and the mounting bracket to which it is attached
. Look for damage caused by arcing or signs that the structure has been overheated
. Also look for a colour change of the protective treatments on the structure. No lateral movement of the earth post is permissible. (b) Examine the attachment of the nacelle horizontal support on the same mounting bracket. Look fo r damage caused by arcing or signs that the linkage has been overheated. (c) If any movement or damage is apparent then th is must be repaired before further flight. Report all findings of damage to:- Repair Drawing Office, BAE Systems (Operations) Limited, Prestwick International Airport, Ayrshire , KA9 2RW, Scotland
. G ive the aircraft tail number, flying hours and details of the damage
. Request a repair scheme
. (d) Inspect the earth cables for the generator and propeller de-ice systems . Look for signs that the cable insulation has been overheated. Look for arcing damage or signs that the terminal tags have been ORIG INAL ISSUE : SEP 27/11 Revision 3: 1 61 h June 2014 J41-24-043 PAGES

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### SERVICE BULLETIN overheated. Replace damaged cables and retest systems affected as appropriate. (e) Check torque load of the earth post stiff nut to 200 lbt.in. (22.6 Nm.) (3) Refer to the procedure in Appendix 3 for the high-current millivolt-drop test. Alternatively, use a high current micro-ohmmeter such as a Megger MOM2 or equivalent and follow the manufacturer's instructions for high current measurements. (a) Do a high-current millivolts-drop test for the earth bolt EP2 (EP4) using a nominal test current of 100 amp. EITHER 

## 1 Measure the resistance between the earth bolt and the adjacent primary structure. The resistance must not be greater than 200 micro-ohms
. OR 

## .2 Measure the resistance between the earth bolt and the bracket, and measure the resistance between the bracket and the adjacent primary structure. The resistance for each measurement must not be greater than 100 micro-ohms (4) If any resistance measurement is found to be in excess of the quoted limits, then steps must be taken to investigate the source of the high resistance and to clean all the surfaces to achieve the requisite resistance value before further flight. (5) Complete the record sheets attached to this bulletin in Appendices 1 and 2, and send the results to BAE Systems at the address shown. C
. Recovery (1) Remove all materials, tools and equipment. Make sure work area is clean. (2) Refer to the AMM Chapters 06 and 71. Install the inboard fairing panel 414AR on the left engine and the outboard fairing panel 424AR on the right engine. (3) Remove warning notice from the flight compartment. (4) Restore electrical power to the aircraft. (5) Aircraft records: Add service bulletin number 'J41 -24-043' to the aircraft records. NOTE: Operators are reminded of the necessity to inform the Business Support Team , Technical Publications, BAE SYSTEMS, Regional Aircraft , Prestwick International Airport, Ayrshire, KA9 2RW, SCOTLAND, of the accomplishment of this SB in order to obtain the necessary revisions for the affected manuals, see paragraph 1.l. Publications Affected, of this SB. J41-24-043 ORIGINAL ISSUE : SEP 27/11 PAGE 6 Revision 3: 161 h June 2014GENERATOR CABLE

NUT NAS509-6

WASHER

SP47J

BRACKET 14157435-7 LEFT 14157436-8 RIGHT 

## IAe JETST.REAJII S.n11s 4fiJIJ SERVICE BULLETIN

NUT HW14-6

EARTH BOLT PKS1017-6 FRONT SPAR (REF) PROPELLER DE -ICE CABLE

**~arth** Post Installation EP2 lett and EP4 right.
ORIGINAL ISSUE: SEP 27/11 Revision 3: 161 h June 2014 FIGURE 1 24-43-10001

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ORIGINAL ISSUE: SEP 27/11 Revision 3: 161 h June 20143. MATERIAL INFORMATION Not applicable.

ORIGINAL ISSUE : SEP 27/11 Revision 3: 161 h June 2014 

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ORIGINAL ISSUE : SEP 27/11 Revision 3: 161 h June 2014

### IIAeJETSTREAIII St/lriiiS 4f(J(J SERVICE BULLETIN 4. CONTINUED AIRWORTHINESS A. Continued Airworthiness Instructions Continued airworthiness instructions applicable to this service bulletin are detailed below. B. Scheduled Maintenance



## c.
D.
E.


### F. (1) The instructions within this Inspection Service Bulletin will be the subject of a MRB review and, as such, may then provide the basis for repeat inspections, with the instructions incorporated in the AMM. Removal Procedures (1) Not applicable. Installation Procedures (1) Not applicable. Test Procedures (1) Not applicable. Trouble Shooting (1) Not applicable
.

ORIGINAL ISSUE: SEP 27/11 Revision 3: 161 h June 2014 J41-24-043 PAGE 11

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ORIGINAL ISSUE: SEP 27/11 Revision 3: 161 h June 2014

### 8AsJETSTREAM Senes4fiJO Appendix 1 - Test Record Sheet. (1) Refer to section 2.B.(2).(a) to (c) of the main bulletin and confirm if any damage was referred to the Repair Design Office (ROO), BAE Systems (Operations) Limited. YES NO (2) Refer to Section 2.B.(2).(d) of the main bulletin and confirm if any cables have been replaced
. YES NO

Details (if applicable)
(3) Refer to Section 2.B.(3)
.(a) of the main bulletin and record the final micro-ohm measurements obtained. Result Location Test Number Limit (micro-ohms) (micro-ohms) Left Wing Either 1 (Earth Bolt to Structure) < 200 Or 2 (Earth Bolt to Bracket) < 100 And 2 (Bracket to Structure < 100 Right Wing Either 1 (Earth Bolt to Structure) < 200 Or 2 (Earth Bolt to Bracket) < 100 And 2 (Bracket to Structure) < 100 (4) Also , record here whether any remedial action e.g. cleaning was required to achieve the above measurements. Left Wing YES NO Right Wing YES NO (5) Send the results to BAE Systems (Operations) Limited (see Appendix 2).

ORIGINAL ISSUE: SEP 27/11 Revision 3 : 161 h June 2014 

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ORIGINAL ISSUE: SEP 27/11 Revision 3: 161 h June 2014

## .8AsJETSTREAM Sel'ies 4flll1 Appendix 2- Inspection Report. Complete and return this form and the form in Appendix 1 to:- Customer Technical Support (Building 37) , BAE Systems (Operations) Limited , Prestwick International Airport, Ayrshire, KA9 2RW, Scotland. Fax+ 44 (0) 1292 675432 E-mail raengliaison@baesystems.com Operator Aircraft Registration Constructor's Number Flight Hours Landings Inspection Date Findings

Brief details of Test Equipment used

ORIGINAL ISSUE: SEP 27/11 Revision 3: 161 h June 2014 J41-24-043 PAGE15J41-24-043 PAGE 16 

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ORIGINAL ISSUE: SEP 27/ 11 Revision 3: 161 h June 2014A. General 

## lAs JETSTREAIII Senes4,PP Appendix 

### 3- Procedure for High-Current Millivolt-Drop Test.
NOTE: The following procedure is applicable to the left earth post installation EP2 and the right earth post installation EP4. NOTE: The following procedure is a modified version of the test in AMM 20-21-00 page 210 Subtask 20-21-00-760-004. NOTE: As an alternative to this procedure, operators can use a high current microohmmeter such as a Megger MOM2 or equivalent and follow the manufacturer's instructions for high current measurements. B. Equipment Item Description 20-0002 Ammeter, 150 amp 20-0007 Millivolt meter 20-0009 Variable Power Supply Unit (VPSU), 0 to 150 amp C. Test WARNING: BECAUSE OF THE CONFINED SPACE IN WHICH THIS TEST MAY NEED TO BE PERFORMED, CARE MUST BE TAKEN TO ENSURE THAT THE OPERATOR IS REMOTE FROM THE TEST AREA WHEN APPLYING THE HIGH CURRENT. (1) Make sure the fasteners and the probes are clean. (2) Connect the millivolt meter probes as shown in figure 1 . NOTE: The millivolt meter probes should be bolted in place to ensure the operator can remain remote from the test area. Caution: The power connections must be bolted onto the structure and onto the earth post. Caution: Ensure that appropriately sized cables are used for the test. (3) Connect the VPSU and the ammeter and bolt in place as shown in figure 1. Make su re that the fasteners are near to each side of the electrically bonded joint, but not on it.

ORIGINAL ISSUE: SEP 27/11 Revision 3: 161 h Ju ne 2014 J41-24-043 PAGE17

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**4~/JIJ** SERVICE BULLETIN (4) Attach the test leads for the millivolt meter to positions near to each side of the electrically bonded joint, but not on it. NOTE: If the use of probes is unavoidable, then apply heavy pressure to the probes whilst taking the measurements. (5) Adjust the VPSU to provide a test current of 100 amps. WARNING: MAKE SURE THE TEMPERATURE OF THE JOINT DOES NOT INCREASE TO MORE THAN 40 DEGREES CELSIUS (104 DEGREES FARENHEIT) ABOVE THE LOCAL TEMPERATURE. (6) After a minimum of one minute, record the millivolt meter reading obtained. (7) Adjust the VPSU until no current flows and then disconnect the VPSU, the millivolt meter and the ammeter. (8) Remove all of the equipment. (9) Make sure the resistance is within the following limits:-

J41-24-043 PAGE 18 (a) If the resistance measurement is between the earth bolt and the adjacent primary structure, then the resistance must not be greater than 200 microohms. OR (b) If the resistance measurement is between the earth bolt and the bracket, and then between the bracket and the adjacent primary structure then the resistance for each measurement must not be greater than 100 micro-ohms. NOTE: To get the resistance of the electrically bonded joint, in micro-ohms, divide the voltage by the current: - e .g . 7.5 millivolts divided by 100 amps= 75 micro-ohms.

ORIGINAL ISSUE: SEP 27/11 Revision 3: 161h June 2014BOLTED CONNECTION EARTH POST

PSU VARI ABLE PROBE

ORIGINAL ISSUE: SEP 27/11 Revision 3: 16'hJune 2014 

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E

ARTH R ETURN STRUCTURE

PROBE

Schematic - High current test FIGURE 1 BOLTED CONNECTlON

24-43-1 0007

J41-24-043 PAGE19

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ORIGINAL ISSUE : SEP 27/ 11 Revision 3: 161 h June 2014

## ACCOMPLISHMENT REPORT 

# ISERVICE BULLETIN NUMBER 

## J41-24-043

TITLE: ELECTRICAL POWER- DC GENERATION - OVERHEAT FAILURE OF EARTH POSTS (LEFT AND RIGHT). TO: THE 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.