## Service Bulletin Fokker 50/60

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.

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Jan 13/11 SBF50-53-062 Page 1 FUSELAGE Rear Fuselage - The Terminating Repair of the Skin Lap-joint at the Water Service Panel in the Left-Hand Rear Fuselage

1. Planning Information A. Effectivity (1) F27 Mark 050 aircraft serial numbers: 20103 thru 20252, 20254 thru 20267, 20270 thru 20279, 20281, 20283 thru 20286, 20288 thru 20317, 20328, 20331, 20333 and 20335.

NOTE : This Service Bulletin is not applicable to Mark 0502 and 0604 aircraft.

(2) Production version of this modification: Not applicable. B. Concurrent Requirements (1) Not applicable.

C. Reason (1) One operator reported a clearly visible crack in a fuselage lap joint just forward of the ice protection plate. Fokker Services determined in a review of all fuselage lap-joints that a crack on this specific location is not critical due to:

− The visibility of the crack

− The local damage tolerance characteristics

− The frequent inspections, with an interval between 2 500 and 4 000 flight cycles(MRB tasks 530000-00-01, -02 and -04) around the chine line close to this lapjoint. (2) In the same review, however, a critical location was found. At this location the cabin pressure causes severe loads to the lap-joint construction.

## Service Bulletin Fokker 50/60

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.

SBF50-53-062 Jan 13/11 Page 2 This is due to the presence of a skin cut-out of 300 by 200 mm for a water service panel. The location of this lap joint section is at stringer 106 between fuselage frames15825 and 16275. The reinforcement plate for this skin cut-out ends just on the lapjoint. (3) Analysis of this lap-joint section shows that due to the high local loads cracks can occur from about 47 000 flight cycles in the Inner skin. The 1,6 mm thick outer skin will cover a possible crack in the 0,8 mm thick inner skin and a crack will therefore not be visible. The construction is such that when a crack grows the loads further increase which can result in an exponential crack growth rate if the crack is not timely detected. The inner skin can fail over a certain length and, due to cabin differential pressure the floor can fail also. (4) To detect cracks in this lap-joint section Service Bulletin SBF50-53-061 tells you to do a one-time Low-Frequency Eddy Current inspection if your aircraft have exceeded 45 000 flight cycles on the date of issue of Service Bulletin SBF50-53-061. A revision of the Fokker 50/60 Maintenance Review Board Document (MRB) will introduce a task for subsequent inspections. Furthermore the MRB will also give the threshold of this inspection for those aircraft which hav e not yet accumulated 45 000 flight cycles on the date of issue of Service Bulletin SBF50-53-061. (5) If you have found a crack (or cracks) dur ing accomplishment of Service Bulletin SBF50-53-061 this Service Bulletin tells you how to make a terminating repair. The new repetitive MRB inspections mentioned above will then not be applicable. (6) This Service Bulletin can also be accomplished as a modification (also for aircraft for which SBF50-53-061 is not effective) to avoid the one-time inspection of Service Bulletin SBF50-53-061 and/or the new repetitive MRB inspections mentioned above. D. Description (1) This Service Bulletin tells you how to: - Cut the lap-joint, outer and inner skin, at two (2) locations. - Remove the applicable and/or cracked part of the inner skin. - Install an insert for the removed part of the inner skin. - Apply an external repair patch with repair doublers. E. Compliance (1) Optional. NOTE: Refer to recommended SBF50-53-061 for those situations where repair is required. F. Approval (1) The technical content of this document is approved under the authority of DOA nr. EASA.21J.059.

## Service Bulletin Fokker 50/60

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.

Jan 13/11 SBF50-53-062 Page 3 G. Manpower (1) Approximately 16 man-hours are necessary to do this Service Bulletin on one aircraft. This table of manpower will help you to schedule and do this Service Bulletin:

Instructions Men Man-hours Elapsed time (hours) Removal 2 6,0 3,0 Modification Inspection - - - Installation 2 10,0 5,0 Testing Total 16,0 8,0 NOTE : This estimate does not include the time necessary for the paint to dry and/or the sealant to cure. (2) The estimated hours are for direct labor done by experienced personnel. They are calculated based on the conditions given in SBF50-00-001 (Service Bulletin Introduction, section 2.C., "Manpower"). H. Weight and Balance (1) Weight change: + 0,92 kg (+ 2.04 lb). Index change: + 0.044.

I. Electrical Load Data (1) Not changed. J. Software Accomplishment Summary (1) Not applicable.

K. References (a) Fokker 50/60 Aircraft Maintenance Manual (AMM). Fokker 50/60 Illustrated Parts Catalog (IPC) Fokker Standards & Process Manual (SPM). Fokker 50 Structural Repair Manual (SRM) Fokker 50/60 Maintenance Review Board (MRB) document Fokker Consumable Material List (CML) Fokker 50/60 Service Bulletin (SB): - SBF50-53-061. Fokker internal reference(s): - ECR015731.

## Service Bulletin Fokker 50/60

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.

SBF50-53-062 Jan 13/11 Page 4 L. Publications Affected (1) This SB affects the publications listed below: (a) Maintenance Documentation

Not affected.

(b) Maintenance Programs - Fokker 50/60 Maintenance Review Board (MRB). - Fokker 50/60 Maintenance Planning Document (MPD) - Fokker 50/60 Customized Maintenance Program (CMP). (c) Special Instructions for Continued Airworthiness (ICA) The effect of this Service Bulletin on the special ICA is as follows:

YES NO - Electrical Wiring Interconnection System (EWIS) - X - Fuel Tank Safety (FTS) - X - Damage Tolerance of Fatigue Critical Structure X - NOTE : If “YES”, when not already incorporated, the changed ICA will be incorporated in the MRB document within one calendar year from the date of issue of this Service Bulletin. Until then, no actions are required. (d) Operational Documentation

Not affected.

(2) Report to Fokker Services that this SB has been carried out on the applicable aircraft. Refer to “MyFokkerFleet.com/Aircraft/Modification”. (3) For incorporation of this Service Bulletin in your documentation refer to SBF50-00-001 (Service Bulletin Introduction, section 4 "Incorporation of Service Bulletins in Documentation of Fokker Services"). M. Interchangeability or Intermixability of Parts (1) Not applicable.

## Service Bulletin Fokker 50/60

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.

Jan 13/11 SBF50-53-062 Page 5 2. Material Information A. Material – Price and Availability (1) The materials are local source items. B. Material Required (1) These parts, which are necessary to complete this Service Bulletin on 1 aircraft, are not part of the mod kit.

New Part Number Qty Keyword Info Old Part Number Instructions/ Disposition

- * Lint-free cloth Fk05-044** - Local source Methyl Ethyl Ketone (MEK)*** * Cleaning solvent Fk11-003 - Local source Alodine 1201 * Conversion powder (Fk13-003D)** - Local source PR1436G-A * Sealing compound (Fk09-016)** - Local source Aerodur S15/60 * Primer (Fk07-008)**/*** - Local source

MS20470AD4 90* Rivet - - Local source NAS1097AD5 250* Rivet - - Local source - * corrosion resistant steel (or stainless steel) strip. ~20 x 50 mm. ~t = 0,4 mm. - Local source

F0N18-9151S04 30* Conical washers (or rivet heads) - Local source F0N18-9151S05 80* Conical washers (or rivet heads) - Local source Alclad 2024T3 * Aluminum sheet, ~700 x 80 mm ~860 x 80 mm ~900 x 100 mm. T = 0,8 mm (= 0.032 inch) - Local source

Alclad 2024T3 * Aluminum sheet, ~820 x 180 mm. T = 1,4 mm (= 0.056 inch) - Local source

NOTES : * Use as much as necessary ** Refer to the CML for material numbers. *** Or equivalent. (2) These mod kit parts are necessary to do this Service Bulletin on 1 aircraft. (a) Not applicable. C. Tooling – Price and Availability (1) Not applicable.

## Service Bulletin Fokker 50/60

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.

SBF50-53-062 Jan 13/11 Page 6 D. Drawings Required (1) Not applicable.

## Service Bulletin Fokker 50/60

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.

Jan 13/11 SBF50-53-062 Page 7 3. Accomplishment Instructions

General: - For CML material number references, refer to “Myfokkerfleet.com/Documentation/CML”.

- For Standards and Process Manual (SPM) references, refer to

“Myfokkerfleet.com/Documentation/SPM”. - For the application of Alodine 1201 (Fk13-003D), refer to the AMM, chapter 51-12-00 or SRM

chapter 51-24-01. - For the application of Sealing compound PR1436G-A (Fk09-016) refer to the AMM,

chapter 51-23-00. - For the removal/installation of solid rivets, refer to the SRM, chapter 51-40-02. - For the application of Primer and Paint, refer to the AMM, chapter 51-24-00. - For drilling and countersinking procedures, refer to the SRM, chapter 51-22-01. WARNING : BE CAREFUL WHEN YOU USE THE CONSUMABLE MATERIALS. OBEY THE INSTRUCTIONS AND MANUFACTURER'S HEALTH AND SAFETY INSTRUCTIONS.

A. Gain access to the repair area. (1) Remove passenger seats, if applicable, ref. AMM chapter 25-21-01. (2) Remove galley if applicable, ref. AMM chapter 25-31-00 or 25-32-00. (3) Remove floor panel(s), ref. AMM chapter 53-71-01. Refer to figure 1. B. Cut the lap-joint, outer and inner skin, at two (2) locations. (1) Clean the lap joint between approx. fuselage station 15600 and 16450. Remove the paint scheme if necessary to see the existing solid rivet heads. Use: - A.R. Lint-free cloth Fk05-044 - A.R. Methyl Ethyl Ketone (or equivalent) Fk11-003 (2) Clean the inside at stringer 106 where the cut in the skins must be made and the (6 mm) holes must be drilled. Use: - A.R. Lint-free cloth Fk05-044 - A.R. Methyl Ethyl Ketone (or equivalent) Fk11-003 (3) Remove/drill out the existing rivets of the lap joint between approx. station 15600 and 16450. (4) Temporary install a sacrificial thin corrosion resistant steel (or stainless steel) strip between the stringer 106 horizontal skin-flange and the inner skin to avoid cutting in the stringer flange. Use: - 1 corrosion resistant steel (or stainless steel) strip. ~20 x 50 mm. T= ~ 0,4 mm.

## Service Bulletin Fokker 50/60

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.

SBF50-53-062 Jan 13/11 Page 8 (5) Drill the two (2) holes, diameter 6,0 mm (or 1⁄4 inch), at the indicated locations on figure 1. (6) Cut the lap joint outer- and inner-skin according the outline on figure 1, starting at the drilled holes of 6 mm (or 1⁄4 inch) from step (4). (7) Remove the sacrificial thin corrosion resistant steel (or stainless steel) strip. Refer to figure 2. C. Remove the applicable and/or cracked part of the inner skin. (1) Remove the sealing compound between the lap joint skins from fuselage station 15600 to station 16450. (2) Carefully lift the outer skin a bit (~10 mm) on both sides of the cuts from step B. (3) Enlarge the cut in the inner skin with a radius of 8 mm and 40 mm below the lap joint, according to figure 2. Let the outer skin retain its old position. (4) De-burr the edges of all cut skins. (5) If this Service Bulletin is accomplished in place of Service Bulletin SBF50-53-061 retain the removed part of the inner skin for further investigation by Fokker Services B.V. See step J. Refer to figure 3. D. Install an insert for the removed part of the inner skin. (1) Manufacture a new skin insert from local source material according to figure 3. Use: - 1 Alclad 2024T3, ~700 x 80 mm. T = 0,8 mm (= 0.032 inch) (2) De-burr the edges of the skin insert. Refer to figure 4. E. Apply external repair doublers. (1) Manufacture new repair doublers from local source material according to figure 4. Use: - 1 Alclad 2024T3, ~900 x 100 mm. T = 0,8 mm (= 0.032 inch) - 1 Alclad 2024T3, ~860 x 80 mm. T = 0,8 mm (= 0.032 inch) (2) Round off the edges of the repair doublers with a radius of 0,8 mm (R=t). (3) Mark the new rivet locations on the repair doublers, use a pitch of 16 - 20 mm according to Figure 4.

## Service Bulletin Fokker 50/60

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.

Jan 13/11 SBF50-53-062 Page 9 Refer to figure 5. F. Apply an external repair patch with repair doublers. (1) Manufacture an external repair patch from local source material according to figure 5. Use: - 1 Alclad 2024T3, ~820 x 180 mm. T = 1,4 mm (= 0.056 inch) (2) Temporary install the repair doublers and the external repair patch on the proper fuselage positions and mark the new rivet locations according to figure 5, use a pitch of 16 – 20 mm, according to existing rivet pattern. (3) Chamfer the edge of the repair patch with a radius of 1,4 mm (R=t). Refer to figures 4 and 5. G. Install inner skin insert, repair doublers and external repair patch. (1) Temporary install the inner skin insert, repair doublers and the external repair patch on the proper fuselage positions. (2) Pick up existing rivet locations and drill new rivet holes at the marked locations. (3) Remove the repair parts and de-burr the holes in the inner skin insert, repair doublers and external repair patch and restore the protective surface treatments of the skins, repair parts and holes. Use: - AR Conversion powder Alodine 1201 (Fk13-003D) - AR Primer (not in holes) Aerodur S15/60 (Fk07-008) (4) Install conical washers (or rivet heads) in the existing countersinkings of the lap joint and at water supply panel reinforcements with interfaying sealing compound. Use: - AR Sealing Compound PR1436G-A (Fk09-016) - AR Conical washers (or rivet heads) F0N18-9151S04 - AR Conical washers (or rivet heads) F0N18-9151S05 (5) Install the inner skin insert, repair doublers and external repair patch on the proper fuselage positions with interfaying sealing compound and solid rivets. Use: - AR Sealing Compound PR1436G-A (Fk09-016) - 90 Rivet MS20470AD4 - 250 Rivet NAS1097AD5 (6) Restore paint scheme, refer to AMM, chapter 51-24-00. H. Remove the tools, materials and equipment from the work area. Make sure that the work area is clean.

## Service Bulletin Fokker 50/60

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.

SBF50-53-062 Jan 13/11 Page 10 I. Re-install passenger equipment. (1) Re-install floor panel(s), if applicable, ref. AMM chapter 53-71-01. (2) Re-install galley, if applicable, ref. AMM chapter 25-31-00 or 25-32-00. (3) Re-install passenger seats, ref. AMM chapter 25-21-01.

J. Send cracked inner skin to Fokker Services. (1) If the cracked inner skin was removed at step C. (5) send the retained part of the inner skin for further investigation to Fokker Services B.V to the following address:

Fokker Services B.V. Attn: Mr. Jack Hoogkamer Structures & Interior NV01-231 Technical Services P.O. Box 231 2150 AE Nieuw-Vennep The Netherlands.

## Service Bulletin Fokker 50/60

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.

Jan 13/11 SBF50-53-062 Page 11The Cut-out in both Lap Joint Skins.Figure 1

## Service Bulletin Fokker 50/60

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.

SBF50-53-062 Jan 13/11 Page 12The Cut-out in the Inner Lap Joint Skin.Figure 2

## Service Bulletin Fokker 50/60

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.

Jan 13/11 SBF50-53-062 Page 13The New Skin Insert for the Inner Lap Joint Skin.Figure 3

## Service Bulletin Fokker 50/60

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.

SBF50-53-062 Jan 13/11 Page 14The Repair Doublers for the Lap Joint Terminating Repair.Figure 4

## Service Bulletin Fokker 50/60

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.

Jan 13/11 SBF50-53-062 Page 15The Repair Patch for the Lap Joint Terminating Repair.Figure 5