## Service Bulletin Fokker F28

Copyright All rights reserved by Fokker Services B.V. (The Netherlands). This document has been supplied by Fokker Services B.V . to its customers on a confidential basis subject to the provisions of an agreement. Reproduction or disclosure to third parties of this document or any part thereof, or the use of any information contained there in for purposes other than explicitly allowed by the aforesaid agreement, is not permitted except with the prior written permission of Fokker Services B.V.

May 06/10 SBF28-57-097 Revision 1, June 10/10 Page 1 1. Planning Information A. Effectivity (1) F28 aircraft serial numbers: 11003 thru 11241 11991 and 11992. B. Concurrent Requirements (1) Not applicable.

C. Reason (1) The design review of the F28 Mk 1000(C)/2000/3000(C)/4000 fuel system in accordance with the guidelines related to FAA SFAR 88 and JAA INT/POL/25/12 revealed that an unsafe condition could develop in the wing tanks. Under certain conditions, insufficient clearance between the wiring along the Fuel Quantity Tank Units (FQTU’s) and the local reinforcing structure around the upper skin cut out may result in an ignition source in the wing tank vapor space. (2) A one-time inspection to investigate if a clearance of 3 mm (0.12 inch) or more is available between the FQTU probes wiring and the surrounding reinforcement structure of the wing upper skin is recommended. Non-compliance to the minimum clearance requires rework of the surrounding structure to remove the possibility of an ignition source and therewith become compliant with the Fuel Tank Safety Program requirements.

Page 1 2 3 4 5 6 7 8 9 Revision 1 1 1 1 1 1 1 1 1 WINGS

“This Service Bulletin is part of the Fuel Tank Safety Program”

Structure - A one-time Inspection and, if necessary, Rework of the Holes in the Outer Wing Upper Skin Panel Reinforcement Structure for the Outer Wing Fuel Quantity Tank Units

## Service Bulletin Fokker F28

Copyright All rights reserved by Fokker Services B.V. (The Netherlands). This document has been supplied by Fokker Services B.V . to its customers on a confidential basis subject to the provisions of an agreement. Reproduction or disclosure to third parties of this document or any part thereof, or the use of any information contained there in for purposes other than explicitly allowed by the aforesaid agreement, is not permitted except with the prior written permission of Fokker Services B.V.

SBF28-57-097 May 06/10 Page 2 Revision 1, June 10/10 Reason for Revision (1) This revision is made to: - Add a NOTE to the compliance. D. Description (1) This Service Bulletin tells you how to:

- Inspect the upper wing skin FQTU hole reinforcement structure for a minimum clearance of 3 mm (0.12 inch) with the FQI probe wiring.

- Rework the upper wing skin FQTU hole reinforcement structure. E. Compliance (1) Recommended. Fokker Services recommends the accomplishment of this Service Bulletin not later than May 1, 2017.

NOTE 1: Because of the required tank opening it is efficient to do this Service Bulletin concurrently with a scheduled tank inspection before the above compliance date.

NOTE 2 : It is expected that the EASA will issue an Airworthiness Directive (AD)with respect to this subject with the same compliance terms. Refer to the EASA website for the publication of a Proposed Airworthiness Directive for comments. F. Approval (1) The technical content of this document is approved by EASA or under the authority of DOA nr. EASA.21J.059. G. Manpower (1) Approximately 27 man-hours are necessary to do this Service Bulletin on 1 aircraft. This table of manpower will help you to schedule and do this Service Bulletin:

Instructions Men Man-hours Elapsed time (hours) Inspection 2 6 3 Removal Modification 2 12 6 Installation 2 8 4 Testing 1 1 1

Total 27 14

## Service Bulletin Fokker F28

Copyright All rights reserved by Fokker Services B.V. (The Netherlands). This document has been supplied by Fokker Services B.V . to its customers on a confidential basis subject to the provisions of an agreement. Reproduction or disclosure to third parties of this document or any part thereof, or the use of any information contained there in for purposes other than explicitly allowed by the aforesaid agreement, is not permitted except with the prior written permission of Fokker Services B.V.

May 06/10 SBF28-57-097 Revision 1, June 10/10 Page 3 NOTE 1 : This estimate does not include the time to gain access and ventilate the fuel tanks to bring the fuel/air mixture inside the tank below the Lower Explosion Limit (LEL), nor the time necessary for the paint to dry and/or the sealant to cure. NOTE 2 : This estimate includes the man-hours required to rework all 20 reinforcement plates. The man-hours will be lower when less reinforcement plates need to be reworked. (2) The estimated hours are for direct labor done by experienced personnel. They are calculated based on the conditions given in SBF28-00-001 (Service Bulletin Introduction, section 2.C., "Manpower"). H. Weight and Balance (1) Weight change: None Index change: None. I. Electrical Load Data (1) Not affected. J. Software Accomplishment Instructions (1) Not applicable. K. References (1) F28 Maintenance Manual (MM): - TR 28-34 - TR 28-43 - TR 28-54 F28 Structural Repair Manual (SRM) Fokker internal reference(s): - ECR 015105 F28 Service Bulletin: - SBF28-28-050. L. Publications Affected (1) This SB affects the publications listed below: (a) Maintenance Documentation

Not affected. (b) Maintenance Programs

Not affected.

(c) Special Instructions for Continued Airworthiness (ICA)

## Service Bulletin Fokker F28

Copyright All rights reserved by Fokker Services B.V. (The Netherlands). This document has been supplied by Fokker Services B.V . to its customers on a confidential basis subject to the provisions of an agreement. Reproduction or disclosure to third parties of this document or any part thereof, or the use of any information contained there in for purposes other than explicitly allowed by the aforesaid agreement, is not permitted except with the prior written permission of Fokker Services B.V.

SBF28-57-097 May 06/10 Page 4 Revision 1, June 10/10 The effect of this Service Bulletin on the special ICA is as follows :

YES NO - Fuel Tank Safety (FTS) - X*

NOTE * : A CDCCL (Critical Design Configuration Control Limitation) is already applicable and has been introduced through SBF28-28-050. (d) Operational Documentation

Not affected. (2) For incorporation of this Service Bulletin in your documentation refer to SBF28-28-001 (Service Bulletin Introduction), section 4 "Incorporation of Service Bulletins in Documentation of Fokker Services". M. Interchangeability or Intermixability of Parts (1) Not applicable.

2. Material Information A. Material – Price and Availability (1) Not applicable. B. Material Required (1) Not applicable. C. Tooling – Price and Availability (1) Not applicable. D. Drawings Required (1) Not applicable.

## Service Bulletin Fokker F28

Copyright All rights reserved by Fokker Services B.V. (The Netherlands). This document has been supplied by Fokker Services B.V . to its customers on a confidential basis subject to the provisions of an agreement. Reproduction or disclosure to third parties of this document or any part thereof, or the use of any information contained there in for purposes other than explicitly allowed by the aforesaid agreement, is not permitted except with the prior written permission of Fokker Services B.V.

May 06/10 SBF28-57-097 Revision 1, June 10/10 Page 5 3. Accomplishment Instructions

General

- Instructions are written for the LH side but are similar for the RH side. If the instructions for the RH side differ from the LH side, this will be mentioned between brackets.

WARNING : BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE OPERATOR’S AND MANUFACTURER’S HEALTH AND SAFETY INSTRUCTIONS.

WARNING : OBEY THE SAFETY PRECAUTIONS. JET FUEL IS EXPLOSIVE AND POISONOUS.

WARNING : BEFORE ENTERING FUEL TANKS ENSURE THAT ALL SAFETY PRECAUTIONS DETAILED IN MM CHAPTER 28-11-00 ARE OBSERVED. A. Gain access to the inspection area as follows: (1) Defuel the fuel tanks. For defueling refer to MM chapter 12-28-02 or MM chapter 12-28-03. (2) Vent the fuel tanks. Refer to MM chapter 28-11-00. (3) Pull and safety the following circuit breakers: (a) Booster pumps: LH TANK PUMP 1 (FWD) and PUMP 2 (AFT), and RH TANK PUMP 1 (FWD) and PUMP 2 (AFT). (b) QUANT IND LH and RH TANK. (4) Remove and keep the following wing tank access panels in the LH wing (RH wing) lower skin. Refer to MM chapter 06-30-07. - 71A (72A) to obtain access to Fuel Quantity Tank Units 9 and 10. - 73A (74A) to obtain access to Fuel Quantity Tank Units 7 and 8. - 73B (74B) to obtain access to Fuel Quantity Tank Unit 6. - 73C (74C) to obtain access to Fuel Quantity Tank Unit 5. - 73D (74D) to obtain access to Fuel Quantity Tank Units 3 and 4. - 73E (74E) to obtain access to Fuel Quantity Tank Unit 2. - 73H (74H) to obtain access to Fuel Quantity Tank Unit 1. B. Inspect the gap between the FQTU wiring harness and the outer wing FQTU hole reinforcement structure as follows: (1) On the inside of the fuel tank measure the distance at any part of the FQTU between the electrical wiring connections on FQTU no. 1 thru 10 and the reinforcement plate around the FQTU. See figure 1.

## Service Bulletin Fokker F28

Copyright All rights reserved by Fokker Services B.V. (The Netherlands). This document has been supplied by Fokker Services B.V . to its customers on a confidential basis subject to the provisions of an agreement. Reproduction or disclosure to third parties of this document or any part thereof, or the use of any information contained there in for purposes other than explicitly allowed by the aforesaid agreement, is not permitted except with the prior written permission of Fokker Services B.V.

SBF28-57-097 May 06/10 Page 6 Revision 1, June 10/10 (2) The FQTU’s 1 thru 9 can be installed in six different orientations. Loosen, remove and keep the screws and repeat step (1) for each orientation in which the FQTU’s can be installed. (3) Mark the positions on the reinforcement plate where a clearance of less than 3 mm (0.12 inch) is measured. (4) If the gap between the electrical wiring connections and the reinforcement plate with the FQTU in all possible positions of installation is 3 mm (0.12 inch) or more: install the FQTU in accordance with MM chapter 28-41-01 as changed with Temporary Revision TR28-54. Continue with step F. (5) If the gap on any of the inspected positions is less than 3 mm (0.12 inch), rework of the reinforcement plates at the marked positions in step (3) is required. For instructions on how to rework the reinforcement plate refer to steps C thru F.

C. Gain access to the rework area as follows: (1) Remove and keep the affected FQTU’s from each wing. Refer to MM chapter 28-41-01 as changed with Temporary Revision TR 28-54. D. Modify the reinforcement plates as follows: (1) Rework the reinforcement plates installed on the bottom side of the upper wing skin to the dimensions marked in step B.(5). Refer to figure 2 for the maximum rework dimensions.

NOTE : When more than one place on a reinforcement plate needs to be reworked, the rework may be carried out by removing the maximum required dimension around the complete circumference of the hole to a maximum of 3 mm (0.12 inch). (2) After rework, deburr and polish the reworked edges of the reinforcement plate.

E. Restore the surface treatment and reinstall the FQTU’s as follows: (1) Restore the surface treatment of the reworked area with Alodine 1201. (2) Restore the tank sealing. Refer to SRM chapter 51-20-0. (3) Install the FQTU’s removed in step C.(1). Refer to MM chapter 28-41-01 as changed with Temporary Revision TR28-54. F. Close up. (1) Perform the tank closure inspection in accordance with paragraph 6 of MM Temporary Revision TR 28-34.

## Service Bulletin Fokker F28

Copyright All rights reserved by Fokker Services B.V. (The Netherlands). This document has been supplied by Fokker Services B.V . to its customers on a confidential basis subject to the provisions of an agreement. Reproduction or disclosure to third parties of this document or any part thereof, or the use of any information contained there in for purposes other than explicitly allowed by the aforesaid agreement, is not permitted except with the prior written permission of Fokker Services B.V.

May 06/10 SBF28-57-097 Revision 1, June 10/10 Page 7 (2) Reinstall the tank access panels removed in step A.(4). Refer to MM chapter 28-11-06 as changed with Temporary Revision TR 28-43. (3) Close the following circuit breakers: (a) QUANT IND LH and RH TANK. (b) Booster pumps: LH TANK PUMP 1 (FWD) and PUMP 2 (AFT), and RH TANK PUMP 1 (FWD) and PUMP 2 (AFT). (4) Refuel the aircraft. For refueling refer to MM chapter 12-28-02 or MM chapter 12-28-03. (5) Inspect the tank access panels for fuel leakage. (6) Calibrate the outer wing tank system. Refer to MM chapter 28-41-00.

NOTE : Calibration is only necessary when a probe has been replaced or when the electrical connections have been loosened.

## Service Bulletin Fokker F28

Copyright All rights reserved by Fokker Services B.V. (The Netherlands). This document has been supplied by Fokker Services B.V . to its customers on a confidential basis subject to the provisions of an agreement. Reproduction or disclosure to third parties of this document or any part thereof, or the use of any information contained there in for purposes other than explicitly allowed by the aforesaid agreement, is not permitted except with the prior written permission of Fokker Services B.V.

SBF28-57-097 May 06/10 Page 8 Revision 1, June 10/10 Typical Electrical Wiring Connections of FQTU Typical Reinforcement Plate

The Location of the FQTU 1 and the Reinforcement Plate Figure 1

## Service Bulletin Fokker F28

Copyright All rights reserved by Fokker Services B.V. (The Netherlands). This document has been supplied by Fokker Services B.V . to its customers on a confidential basis subject to the provisions of an agreement. Reproduction or disclosure to third parties of this document or any part thereof, or the use of any information contained there in for purposes other than explicitly allowed by the aforesaid agreement, is not permitted except with the prior written permission of Fokker Services B.V.

May 06/10 SBF28-57-097 Revision 1, June 10/10 Page 9 Reinforcement Plate

Maximum allowable rework is 3 mm (0.12 inch) around full circumference of hole.

Local rework up to 3 mm (0,12 inch). Use a minimum rework radius of 10 mm (0.039 inch).

The Rework of the Reinforcement Plate Figure 2