Service Bulletin

Fokker 50/60

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Reproduction or disclosure to third parties of this document or any part thereof, or the use of any information contained therein 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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Revision - - - - - - - - - - - - - - - -

Jan 13/11 SBF50-53-061

Page 1

FUSELAGE

Rear Fuselage - A One-Time Inspection 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.

If the aircraft is in the pre-Service 

Bulletin SBF50-53-062-

configuration and has accumulated 

45 000 flight cycles or more on the 

date of issue of this Service 

Bulletin
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 therein for purposes other than explicitly allowed by the aforesaid agreement, is not permitted 

except with the prior written permission of Fokker Services B.V.

SBF50-53-061 Jan 13/11

Page 2

(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. 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 frames 15825 and 16275. The reinforcement plate for this skin 

cut-out ends just on the lap-joint.

(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 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 lap-joint 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 this Service Bulletin tells you to do 

a one-time Low-Frequency Eddy Current inspection. A revision of the 

Fokker 50/60 Maintenance Review Board Document (MRB) will introduce a 

task with an interval for subsequent inspections. Furthermore the MRB will 

give the threshold of this inspection for those aircraft which have not yet 

accumulated 45 000 flight cycles on the date of issue of this Service 

Bulletin.

(5) If you find a crack (or cracks) this Service Bulletin tells you to make a 

terminating repair in accordance with Service Bulletin SBF50-53-062:

Rear Fuselage – The Terminating Repair of the Skin Lap-Joint at the Water

Service Panel in the Left-Hand Rear Fuselage.

The new repetitive MRB inspections mentioned above will then not be 

applicable.

(6) Service Bulletin SBF50-53-062 can also be accomplished as a modification 

in place of SBF50-53-061. In that case you will also avoid the new 

repetitive MRB inspections mentioned above.

D. Description

(1) This Service Bulletin tells you how to:

Clean the inspection area if necessary

Do the Low-Frequency Eddy Current inspection

Write down the inspection results on a reporting sheet (also if you do not 

find cracks)

Send the reporting sheet to Fokker Services B.V.

If applicable, do the terminating repair, or optionally, the modification, in 

accordance with Service Bulletin SBF50-53-062.
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 therein 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 SBF50-53-061

Page 3

E. Compliance

(1) Recommended

Fokker Services recommends the accomplishment of this Service Bulletin as follows:

(1) For aircraft, which have accumulated between 45 000 and 46 000 flight cycles on 

the date of issue of this Service Bulletin:

Within one year after the date of issue of this Service Bulletin.

(2) For aircraft, which have accumulated between 46 000 and 47 000 flight cycles on 

the date of issue of this Service Bulletin:

Within six months after the date of issue of this Service Bulletin.

(3) For aircraft, which have accumulated more than 47 000 flight cycles on the date 

of issue of this Service Bulletin:

Within three months after the date of issue of this Service Bulletin.

NOTE 1: It is expected that 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.

NOTE 2: The accomplishment of SBF50-53-062 in place of SBF50-53-061 within 

the same compliance terms as mentioned above will also constitute 

compliance with the AD requirements.

F. Approval

(1) The technical content of this document is approved under the authority of 

DOA nr. EASA.21J.059.

G. Manpower

(1) Approximately 1,5 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 - - -

Modification

Inspection 1 1,5 1,5

Installation

Testing - - -

Total 1,5 1,5
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 therein for purposes other than explicitly allowed by the aforesaid agreement, is not permitted 

except with the prior written permission of Fokker Services B.V.

SBF50-53-061 Jan 13/11

Page 4

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: None

Index change: None.

I. Electrical Load Data

(1) Not changed.

J. Software Accomplishment Summary

(1) Not applicable.

K. References

(1) Fokker 50 Aircraft Maintenance Manual (AMM)

Fokker 50 Non-Destructive Testing Manual (NDTM)

Fokker Consumable Material List (CML)

Fokker 50/60 Service Bulletin (SB):

- SBF50-53-062

Fokker internal reference:

- ECR015731.

L. Publications Affected

(1) This SB affects the publications listed below:

(1) Maintenance Documentation

Not affected.

(2) Maintenance Programs

Not affected.
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 therein 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 SBF50-53-061

Page 5

(3) 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.

(4) Operational Documentation

Not affected.

(2) 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 therein for purposes other than explicitly allowed by the aforesaid agreement, is not permitted 

except with the prior written permission of Fokker Services B.V.

SBF50-53-061 Jan 13/11

Page 6

2. Material Information

A. Material – Price and Availability

(1) Not applicable.

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

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.

(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 therein 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 SBF50-53-061

Page 7

C. Tooling – Price and Availability

(1) The following equipment was used to develop this procedure:

ITEM SPECIFICATION PARTNUMBER REFERENCE MAKE

(1) Phase analysis EC tester ELOTEST-B1SD S0137* Rohmann

(2) Sliding probe, Reflection 

type,1 – 100 kHz

SPT4039* Servicing Europe 

NDT

(3) Interconnecting cable CR-RE-TF180* Servicing Europe 

NDT

(4) Calibration plate 27-1-6033* Figure 4 and 5** Fokker Services

(5) Ruler – non conductive Local

TABLE 1 - INSPECTION TOOLS.

* Relevant numbers when ordering from Fokker Services BV.

** For local manufacture of calibration plate pn 27-1-6033 refer to figures 4 and 5.

NOTE: Any other equipment may be used, provided that the specification in table 1 and 

the sensitivity requirement as given in step B. table 2 of the Accomplishment 

Instructions are met. Calibration procedure may vary when using other 

equipment.

(2) You can contact your Fokker Services Account Support Manager for the price and 

availability of the equipment

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 therein for purposes other than explicitly allowed by the aforesaid agreement, is not permitted 

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SBF50-53-061 Jan 13/11

Page 8

3. Accomplishment Instructions

General:

WARNING: BE CAREFUL WHEN YOU USE THE CONSUMABLE MATERIALS. OBEY 

THE INSTRUCTIONS AND MANUFACTURER'S HEALTH AND SAFETY 

INSTRUCTIONS.

This procedure describes the low frequency (LF) eddy current sliding probe inspection of the 

rivet row at STR 106 between FRA 15825 and FRA 16275 near the water service panel. 

Cracks can occur in the inner skin panel of the lap joint at the lower corners of the water 

service panel cut-out.

You must do this inspection on the outside of the aircraft

For a general and detailed view of the inspection area refer to figure 1.

A. Do the preparation for the inspection.

(1) Clean the inspection area with a lint-free cloth wet with some cleaning agent

Use:

- A.R. Lint-free cloth Fk05-044

- A.R. Methyl Ethyl Ketone (or equivalent) Fk11-003

(2) Remove chipped and/or excessive paint. Refer to NDTM, Part 1, chapter 51-00-06.

(3) Remove excessive sealant from the edge of the lap joint, if necessary.

B. Do the calibration of the instrument.

(1) Operate the instrument in accordance with the instructions of the manufacturer

NOTE: Table 2 gives the initial settings of the instrument.

Y/X or Y/time base Y/X

Frequency (kHz) 3.0

Axis Spread Y/X (dB) 6/0 (or as required)

Preamplifier (dB) 12

Bandwidth MF

Gain (dB) 25/19 (or as required)

Phase (degrees) As required

Filter (Hz) LP: 50

Gate ON

Alarm OFF

TABLE 2 – INITIAL LF INSTRUMENT SETTINGS
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 therein 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 SBF50-53-061

Page 9

Refer to figures 1, 2 and 3.

(2) Adjust the balance point at 25% Full Screen Height (FSH) as indicated in figure 2(a).

(3) Use a non-conductive ruler, to guide the probe over the calibration plate, in order to make 

straight scan lines. Center the probe over the rivet row at position I of the calibration plate. Refer 

to figure 3.

(4) Balance the instrument and make an adjustment to the Phase to get a horizontal lift-off signal 

as shown in figure 2(a).

(5) Scan from position I in the direction of position II of the calibration plate. Make an adjustment of 

Gain and Axis Spread until the signal of the rivet holes without cracks looks like the signal 

shown in figure 2(a). Familiarize yourself with the signals from different rivet sizes at the 

transition of the Box Area and the Stringer Area. See also figure 1.

(6) Scan with the probe along the rivet centerline at position III of the calibration plate until the 

signal peaks. Crack type A in the Box Area must look like the crack indication of figure 2(b). If 

necessary make an adjustment of Gain and Axis Spread.

(7) Scan with the probe along the rivet center line at position IV to familiarize yourself with the 

signal of a crack type A in the Stringer Area. Refer to figure 2(c).

NOTE: Crack type B is not present in the calibration plate, but it would show an open signature 

like that of figure 2(d).

C. Do the inspection.

Refer to figures 1 and 2.

(1) Use a non-conductive ruler, to guide the probe over the fuselage outer skin, in order to make 

straight scan lines. Center the probe over the rivet row at the beginning of the inspection area 

and balance the instrument. Refer to figure 2.

(2) Scan the inspection area with the probe and monitor the signal. Make a mark of every position 

where the signal exceeds the threshold on the screen and looks like the slot signals of 

figure 2(b), 2(c) or 2(d).

D. Do the interpretation of the inspection results.

Refer to table 2 and figures 1 and 2.

(1) Check the sensitivity settings of the instrument on the calibration plate.

(2) Inspect the suspected part(s) of the inspection area of the fuselage skin again with the probe 

over the center of the rivet line.

NOTE: A possible crack gives a signal which exceeds the threshold on the screen and looks 

like the slot signals of figure 2(b), 2(c) or 2(d).
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 therein for purposes other than explicitly allowed by the aforesaid agreement, is not permitted 

except with the prior written permission of Fokker Services B.V.

SBF50-53-061 Jan 13/11

Page 10

E. Make a record of the inspection results (also if you do not find cracks).

(1) Write down the crack location(s) and orientation, if you find a crack. Write down your 

findings on the reporting form of figure 6.

NOTE: Use rivet number(s) of the reporting form to indicate crack location(s)

(2) Send the reporting form, also if you do not find cracks, to the following address:

The address of Fokker Services, Technical Services is:

Fax number : +31 252 627211, or

E-mail : technicalservices@fokker.com

NOTE 1: Step F. is only necessary if you have found a crack (or cracks).

NOTE 2: However, if you have not found cracks you can do step F. also as an optional 

preventive modification. 

F. Do a repair or modification in accordance with Service Bulletin SBF50-53-062.

NOTE: A one-time 250 flight cycles repair postponement is allowed only in case of an 

indication at one rivet hole at rivets 1 to 6 and/or at one rivet hole at rivets 7 to 11.

G. Repair the paint scheme of the aircraft, if necessary. Refer to AMM, chapter 51-24.
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 therein 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 SBF50-53-061

Page 11

Detailed View of the Inspection Area

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 therein for purposes other than explicitly allowed by the aforesaid agreement, is not permitted 

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SBF50-53-061 Jan 13/11

Page 12

Screen Presentations

Figure 2

In the Box Area

In the Stringer Area
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 therein for purposes other than explicitly allowed by the aforesaid agreement, is not permitted 

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Jan 13/11 SBF50-53-061

Page 13

A Top View of Calibration Plate pn 27-1-6033

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 therein for purposes other than explicitly allowed by the aforesaid agreement, is not permitted 

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SBF50-53-061 Jan 13/11

Page 14

* = TYPICAL DIMENSIONS

A Bottom View of Calibration Plate pn 27-1-6033

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 therein for purposes other than explicitly allowed by the aforesaid agreement, is not permitted 

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Jan 13/11 SBF50-53-061

Page 15

Pos. Descript. T Dimensions Material Notes

Mm mm

1 Sheet 1.6 200 x 100 2024T3 „Outer skin‟

2 Sheet 0.8 200 x 100 2024T3 „Inner skin‟

3 Sheet 1.0 200 x 17 2024T3 „Stringer flange‟ 2x

4 Sheet 1.6 100 x 35 2024T3 „Box flange‟ 

5 Tool nr. - Min. 5 mm Engrave On outer skin ‟27-1-6033‟

6 Defect A - 5.0 mm, 2x EDM /saw cut At „inner skin‟ pos 2, 2x 

7 Sealant 0.2 -

PR1431G or 

PR1436G

Wet install pos. 1-4, 8, 9

8 Rivets 4.0 XBC #5 MS20426AD5 10x

9 Rivets 3.2 XBC #4 MS20426AD4 10x

10 Paint Std - std Standard paint scheme

The Parts List of Calibration Plate pn 27-1-6033

Figure 5
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 therein for purposes other than explicitly allowed by the aforesaid agreement, is not permitted 

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SBF50-53-061 Jan 13/11

Page 16

Draw in the above figure the crack(s) to show location and orientation.

Rivet No. Crack indication (Y/N) Crack type (ref. figure 2)

1 ....

2 ....

3 ....

4 ....

5 ....

6 ....

7 ....

8 ....

9 ....

10 ....

11 ....

Send this Reporting Form to Fokker Services B.V.

Fax: :+31 252 627211, or:

E-mail : technicalservices@fokker.com, or:

Via our website : www.MyFokkerFleet.com

The Reporting Form

Figure 6

Aircraft serial number : ................................

Aircraft registration : ................................

Date of inspection : ................................

Number of flight cycles : ................................

Number of flight hours : ................................

 1 2 3 4 5 6 7 8 9 10 11