# BAE Systems Inspection Service Bulletin 53-239: Revision 5

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- Document: [BAE Systems Inspection Service Bulletin 53-239](https://openairdocs.org/service-documents/bae-systems/sb-53-239.md)
- Title as filed: ISB.53-239R05
- Pages: 52
- PDF: https://openairdocs.org/files/sha256/c7/85/c785a6dcd9790a62126ac1aec0d9ef117516f5ef9a19d77c1e8671a711ad8ea0
- Page: https://openairdocs.org/service-documents/bae-systems/sb-53-239/file/c785a6dcd979

## Text

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### Page 1 (OCR)

BAE SYSTEMS (Operations) Limited, Prestwick International Airport, Ayrshire,
KA9 2RW, Scotland.
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
TRANSMITTAL FOR INSPECTION SERVICE BULLETIN REVISION
SERVICE BULLETIN No.ISB.53-239
DATE: 13-JUN-2012
TITLE: FUSELAGE - INSPECTION OF REAR FUSELAGE AFT SKIN LAP JOINTS FOR
CRACKING.
REVISION: 5  DATE: 02-MAR-2017
ACTIONS
(1)  Remove and discard Inspection Service Bulletin (ISB) complete
at revision 4.
(2) Insert Inspection Service Bulletin complete at revision 5.
REASONS FOR REVISION
(1)  Compliance revised for inspection of stringer 11 with no
repairs (see Table 1).
(2)  Compliance revised for inspection of stringer 11 with repairs
(see Table 1).
(3)  Compliance revised for aircraft that have had stringer 11
inspected i.a.w revision 4 of this ISB (see para.1.D).
(4)  View D arrows deleted (see Drawing 1 and Drawing 2).
(5)  View of typical repairs added and text for reduced inspection
intervals lap joints amended (see Drawing 3).
(6)  Editorial (not highlighted).
INCORPORATION OF THIS REVISION DOES NOT REQUIRE INSPECTIONS
ADDITIONAL TO THOSE DONE AT PREVIOUS REVISIONS OF THIS
INSPECTION SERVICE BULLETIN.
Date: 13-JUN-2012  REVISION TRANSMITTAL SHEET
ISB.53-239
Revision: 5 02-MAR-2017  Page 1 of 2
Printed in England

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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
TRANSMITTAL FOR INSPECTION SERVICE BULLETIN REVISION
SERVICE BULLETIN No.ISB.53-239
This Page Is Intentionally Left Blank.
Date: 13-JUN-2012  REVISION TRANSMITTAL SHEET
ISB.53-239
Revision: 5 02-MAR-2017  Page 2 of 2
Printed in England

### Page 3 (OCR)

BAE SYSTEMS (Operations) Limited, Prestwick International Airport, Ayrshire,
KA9 2RW, Scotland.
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
TITLE: FUSELAGE - INSPECTION OF REAR FUSELAGE AFT SKIN LAP JOINTS FOR
CRACKING.
1.Planning information
A.Effectivity
(1) Aircraft
Aircraft affected by this inspection are defined below:-
BAe 146-301
ALL BAe 146-100, 200, 300 Series
ALL AVRO 146-RJ70, RJ85, RJ100 Series
Check the aircraft technical records for accomplishment of
this inspection before actioning this Inspection Service
Bulletin (ISB).
B. Reason
During climb-out, an AVRO 146-RJ100 recently experienced
pressurization problems. Subsequent investigation identified a
42.87 in. (1089 mm.) long crack in the rear fuselage aft lower
skin at the lap joint at stringer 30 left. In addition to the skin
crack, cracks were found in Frames 41X and 42.
Existing fatigue inspections of the fuselage skin may not detect a
crack growing in this area, which could affect the structural
integrity of the rear fuselage.
Consequently, fleet wide inspection of the rear fuselage skin lap
joints is required.
C.Description
An external eddy current inspection is performed on the rear
fuselage aft skin lap joints at stringers 11, 18 and 30 left and
right and stringer 2 right, between frame 39Y and frame 44.
Inspection aft of frame 44 is not required.
NOTE: There may be external skin repair plates fitted to the
aircraft which obscure the areas subject to inspection or
impede the inspection process. These areas must be inspected
in accordance with (i.a.w.) Appendix 3 of this ISB.
Date: 13-JUN-2012  ISB.53-239
Revision: 5 02-MAR-2017  Page 1 of 16
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
NOTE: For BAe 146-100, BAe 146-200 and BAe 146-300 aircraft with
Large freight doors, lap joints 11 and 18 left forward of
frame 43, and lap joint 2 right forward of frame 42, are
by the large freight door surround skin doublers.
These areas are not to be inspected (see Drawing 2, main
ISB) .
If cracks, corrosion or any other defects are found, contact BAE
SYSTEMS for an approved repair scheme.
D.Compliance
This ISB, at Revision 2 or later, is the subject of EASA
Airworthiness Directive 2013-0207. This Airworthiness Directive
may be subject to revision or supersedure with the publication of
this ISB, at Revision 5. Compliance with this ISB, at Revision 5,
is to be i.a.w. the compliance requirements below:-
Table 1.
Skin Land  Initial  Repair  Repeat  Repeat  Inspection
Inspection, Embodied?  Interval  Interval 146  Method
ALL  RJ Delta  and RJ Pre
Aircraft  P (Mods  Delta P
HCM50070E  (Pre-Mods
or 50070F  HCM50070E and
or  50070F and
HCM50259A) HCM50259A)
Stringer 2, right  10,000 FC  No  4000 FC  7500 FC  Appendix 3
Stringer 2, right  See Note 2  Yes  4000 FC  7500 FC  Appendix 3
See Note
3
Stringer 11 left and  10,000 FC  No  4000 FC  7500 FC  Appendix 3
right (except as shown in
Views A and B in Drawing
3 of the main ISB)
Stringer 11 left and  See Note 2  Yes  4000 FC  7500 FC  Appendix 3
right (except as shown in  See Note
Views A and B in Drawing  3
3 of the main ISB)
Stringer 11 left and  10,000 FC  No  4000 FC  7500 FC
right, as shown in Views
A and B in Drawing 3 of
the main ISB
Date: 13-JUN-2012  ISB.53-239
Revision: 5 02-MAR-2017  Page 2 of 16
Printed in England

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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
Skin Land  Initial  Repair  Repeat  Repeat  Inspection
Inspection,  Embodied?  Interval  Interval 146  Method
ALL  RJ Delta  and RJ Pre
Aircraft  P (Mods  Delta P
HCM50070E  (Pre-Mods
or 50070F  HCM50070E and
or  50070F and
HCM50259A> HCM50259A)
Stringer 11 left and  See Note 2  Yes  2400 FC  4300 FC  Appendix 3
right, as shown in Views  See Note
A and B in Drawing 3 of  3
the main ISB
Stringer 18, left and  10,000 FC  No  4000 FC  7500 FC  Appendix 3
right
Stringer 18, left and  See Note 2  Yes  4000 FC  7500 FC  Appendix 3
right  See Note
3
Stringer 30 left and  10,000 FC  No  4000 FC  7500 FC  Appendix 3
right (except as shown in
Views A and B in Drawing
3 of the main ISB)
Stringer 30 left and  See Note 2  Yes  4000 FC  7500 FC  Appendix 3
right (except as shown in  See Note
Views A and B in Drawing
3 of the main ISB)
Stringer 30 left and  10,000 FC  No  4000 FC  7500 FC  Appendix 2
right, as shown in Views
A and B in Drawing 3 of
the main ISB
Stringer 30 left and  See Note 2  Yes  2400 FC  4300 FC  Appendix 3
right, as shown in Views  See Note
A and B in Drawing 3 of  3
the main ISB
NOTE: (1) FC is defined as Flight Cycles.
NOTE: (2) Aircraft that have been inspected i.a.w. this ISB, at
Revision 3 or earlier, with external skin repair plates
which prevented inspection, do not require any retrospective
inspection.  Those areas will be inspected i.a.w. Table 1,
above, at the next scheduled repeat inspection.
NOTE:  (3) If the repair extends across the lap joint, i.e. it does
not abut it, then no inspection is required, see Note 1 and
View A of Drawing 3 in main ISB.
For aircraft that have inspected stringer 11 as shown in Views A
and B in Drawing 3, with no repair, i.a.w. Revision 4 of this ISB,
Date: 13-JUN-2012  ISB.53-239
Revision: 5 02-MAR-2017  Page 3 of 16
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
using the Appendix 3 inspection method, next inspection will be at
2400 FC for RJ Delta P aircraft, and 4300 FC for all other
aircraft, using the Appendix 2 inspection method. Thereafter the
repeat will be as per Table 1.
For aircraft that have accumulated more than 9000 FC since entry
into service, initial inspection is to be within 1000 FC or 6
months, whichever is earlier.
Inspections previously performed i.a.w. this ISB at initial issue
or EASA AMOC 10041592 may be claimed, but only as the initial
inspections for the skin lands at stringer 30 left and stringer 30
right.
Thereafter, all stringers are to be inspected at the repeat
intervals specified in Table 1.
E. Approval
The technical content of this document is approved under the
authority of DOA Ref.EASA.21J.047.
F.Manpower
To inspect as defined in para. 2. - 3.0 man-hours per aircraft.
This man-hour estimate does not include time for gaining access to
the inspection area.
G. Materials - cost and availability
Not applicable.
H.Tooling - cost and availability
Appropriate staging/access platforms are required to allow close
inspection of all the rear fuselage aft skin lap joints.
Refer to Appendix 2, EQUIPMENT AND MATERIALS.
Refer to Appendix 3, EQUIPMENT AND MATERIALS.
I.Weight and balance
Not applicable.
J. References
Aircraft Maintenance Manual AMM 12-10-24.
Date: 13-JUN-2012  ISB.53-239
Revision: 5 02-MAR-2017  Page 4 of 16
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
K.Publications affected
Not applicable.
L.Electrical load data
Not applicable.
M.Software accomplishment summary
Not applicable.
N.Aircraft noise levels
Not applicable.
Date: 13-JUN-2012  ISB.53-239
Revision: 5 02-MAR-2017  Page 5 of 16
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
This Page Is Intentionally Left Blank.
ate: 13-JUN-201  evision: 5 U2-YAR-2U1  SB. 53-23  ade 6 0t1
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
2.Accomplishment instructions
A. General
(1) The following abbreviations are used within this document:-
AMM - Aircraft Maintenance Manual
i.a.w. - in accordance with.
(2)  Observe all WARNINGS and CAUTIONS appearing in the AMM
referred to in this ISB.
B. Preparation
(1) Refer to AMM 12-10-24 and remove all aircraft electrical
power.
(2) Arrange appropriate staging/access platforms to allow safe
inspection of all the rear fuselage aft skin lap joints.
(3) Remove  dorsal panels 273CT, 275AT, 275BR and 275CR to reveal
lap joint at stringer 2 right.
C. Inspection
(1) Refer to Drawing 1 or Drawing 2 in main ISB, as appropriate.
Perform an external eddy current inspection on the rear
fuselage aft skin lap joints at stringer 11, 18 and 30 left
and right and stringer 2 right, between frame 39Y and frame
44 using the appropriate inspection Method as defined in
NOTE: Inspection aft of frame 44 is not required.
NOTE: Refer to Drawing 2 in main ISB, for BAe 146-10U, BAe
146-200 and BAe 146-300 aircraft with large freight
doors, stringers 11 and 18 left forward of frame 43, and
lap joint 2 right forward of frame 42, are obscured by
the large freight door surround skin doublers.
If cracks,  corrosion or any other defects are found, contact
BAE SYSTEMS for an appropriate repair scheme.
D. Test
Not applicable.
Date: 13-JUN-2012  ISB.53-239
Revision: 5 02-MAR-2017  Page 7 of 16
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
E. Close up
(1)  Make certain work  area is clean, and clear of tools and
miscellaneous equipment.
(2) Install dorsal panels previously removed for access.
(3) Remove staging/access platforms previously arranged for
access.
F. Documentation
(1)  Complete a copy of the Inspection Report (Appendix 1)
attached to this ISB and return by fax or mail.
OR
Return all required Inspection Report details via e-mail.
G.Terminating action
(1) None.
Date: 13-JUN-2012  ISB.53-239
Revision: 5 02-MAR-2017  Page 8 of 16
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
FRAME 43
FRAME 44
FRAME 39Y  FRAME
20100000000  43
FRAME  FRAME
44  39Y
STR 2-
STR 11 RH
FRAME
FRAME  43 FRAME  STR 18 RH
39Y  44
STR 30 RH
• STR 11 LH
STR 18 LH
VIEW LOOKING INBOARD
RIGHT SIDE
STR 30 LH
LAP JOINTS TO BE INSPECTED
STR 2
VIEW LOOKING INBOARD
LEFT SIDE
STR 11 RH.  •STR 11 LH
STR 18 RH T  • STR 18 LH
STR 30 RH  * STR 30 LH
C
VIEW LOOKING AFT
N5323915
AREAS OF INSPECTION, LEFT AND RIGHT - PASSENGER AIRCRAFT
DRAWING 1. (Revised)
Date: 13-JUN-2012  ISB.53-239
Revision: 5 02-MAR-2017  Page 9 of 16
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
FRAME 43
B
FRAME 44
VA
FRAME 39Y
FRAME  FRAME
FRAME 43  FRAME  39Y
44  42
STR 2 RH-
STR 11 RH
STR 18 RH
STR 30 RH
FRAME  FRAME
39Y  43
FRAME
44
VIEW LOOKING INBOARD
- STR 11 LH  RIGHT SIDE
STR 18 LH
STR 2 RH
- STR 30 LH
STR 11 RH.  „STR 11 LH
VIEW LOOKING INBOARD
LEFT SIDE
STR 18 RH - T  ** STR 18 LH
• LAP JOINTS TO BE INSPECTED
STR 30 RH  * STR 30 LH
VIEW LOOKING AFT
B5323916
AREAS OF INSPECTION, LEFT AND RIGHT - AIRCRAFT WITH LARGE FREIGHT DOOR
DRAWING 2. (Revised)
Date: 13-JUN-2012  ISB.53-239
Revision: 5 02-MAR-2017  Page 10 of 16
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
FRAME 42
FRAME 44  AT STRINGER 11 LH & RH, UPTO
6.0 in. (152.4 mm) FORWARD
FRAME  OF THE DOOR FRAME
42
FRAME 39Y  FRAME  FRAME
44  39Y
20100000000  STR 11 RH
FRAME
FRAME  42  FRAME
39Y  44
STR 30 RH
STR 11 LH  AT STRINGER 30 LH & RH,
BETWEEN 3.0 in. (76.2 mm) FORWARD
TO 11.0 in (279.4 mm) AFT OF FRAME 42
STR 30 LH  VIEW LOOKING INBOARD
RIGHT SIDE
LAP JOINTS WHERE REDUCED
VIEW LOOKING INBOARD  INSPECTION INTERVALS ARE
LEFT SIDE  APPLICABLE IF THERE IS A
REPAIR PRESENT
LAP JOINT
REPAIR  LAP JOINT  STR 11 RH.  „STR 11 LH
REPAIR  LAP JOINT
REPAIR
LAP JOINT REPAIRS
TYPICAL
NOTE:
STR 30 RH  STR 30 LH
ON LARGE FREIGHT DOOR AIRCRAFT
STRINGER 11 LH FORWARD OF THE
DOOR DOES NOT REQUIRE INSPECTION.
IF THE REPAIR EXTENDS ACROSS THE  VIEW LOOKING AFT
LAP JOINT, I.E. IT DOES NOT ABUT IT,
N5323908
THEN NO INSPECTION IS REQUIRED
AREAS OF INSPECTION, LEFT AND RIGHT - WITH REDUCED INSPECTION
INTERVALS
DRAWING 3. (Revised)
Date: 13-JUN-2012  ISB.53-239
Revision: 5 02-MAR-2017  Page 11 of 16
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
3 Material information
None .
ate: 13-JUN-201  eV1S1on: 5 02-MAR-201  ade15ot1  SB. 33-23
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
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ate: 13-JUN-201  eV1s1on: 5 02-MAR-201  0de 1 4 0+"  SB .33-2:
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 1
1.INSPECTION REPORT
A.Complete and return this form as detailed
OPERATOR:
AIRCRAFT REGISTRATION:
CONSTRUCTOR'S NUMBER:
FLIGHT HOURS:
LANDINGS:
DATE INSPECTION PERFORMED:
FINDINGS:
To:  Customer Technical Support (Building 37),
BAE SYSTEMS (Operations) Limited,
Prestwick International Airport,
Ayrshire,
KAO 2RW,
Scotland.
Fax + 44 (0) 1292 675432
e-mail raengliaisonabaesystems.com
Date: 13-JUN-2012  ISB.53-239
Revision: 5 02-MAR-2017  Page 15 of 16
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
This Page Is Intentionally Left Blank.
ate: 13-JUN-201  eV1s1on: 5 02-MAR-201  SB .33-2-
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BAE SYSTEMS (Operations) Limited, Prestwick International Airport, Ayrshire,
KA9 2RW, Scotland.
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
TRANSMITTAL FOR INSPECTION SERVICE BULLETIN REVISION
APPENDIX 2
SERVICE BULLETIN No.ISB. 53-239
DATE: 13-JUN-2012
TITLE: EXTERNAL EDDY CURRENT INSPECTION INSTRUCTION FOR THE
EXAMINATION OF THE REAR FUSELAGE AFT SKIN LAP JOINTS.
REVISION: 5  DATE: 02-MAR-2017
ACTIONS
(1) Remove and discard appendix complete at revision 4.
(2) Insert appendix complete at revision 5.
REASONS FOR REVISION
(1)  Note amended to read ¿At Revision 4 and later of this ISB ..
in Drawing 1 and Drawing 2" (see para.1.A.(1)).
(2) Area of inspection clarified (see para.1.B.(1)).
(3) 'Drawing 3' amended to 'Drawing 4' (see para.1.1.(1). (a)).
(4) 'SSID' amended to 'ISB' (see para.1.J.(2).(d)).
(5)  Note deleted referring to aircraft with large freight door
(see Drawing 1).
(6)  Inspection areas clarified and view of typical repairs added
(see Drawing 1 and Drawing 2).
(7)  View B text amended to "  FRAME. AREA TO BE ... (see
Drawing 1 and Drawing 2).
(8)  "D" identifier added next to "LAP JOINT REPAIRS TYPICAL" (see
Drawing 1 and Drawing 2).
(9) Text I----- LAP JOINTS WHERE REDUCED INSPECTION INTERVALS ARE
APPLICABLE deleted (see Drawing 1 and Drawing 2).
(10) View B text amended to "AT STRINGER 11 RH, UP TO ..." (see
Drawing 2).
INCORPORATION OF THIS REVISION DOES NOT REQUIRE INSPECTIONS
ADDITIONAL TO THOSE DONE AT PREVIOUS REVISIONS OF THIS
INSPECTION SERVICE BULLETIN.
Date: 13-JUN-2012  REVISION TRANSMITTAL SHEET
ISB. 53-239
Revision: 5 02-MAR-2017  Page 1 of 2
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
TRANSMITTAL FOR INSPECTION SERVICE BULLETIN REVISION
SERVICE BULLETIN No.ISB. 53-239
This Page Is Intentionally Left Blank.
Date: 13-JUN-2012  EVISION TRANSMITTAL SHEE
. SB. 55-25
Revision: 5 02-MAR-2017  Page 2 of 2
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### Page 21 (OCR)

BAE SYSTEMS (Operations) Limited, Prestwick International Airport, Ayrshire,
KA9 2RW, Scotland.
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 2
TITLE: EXTERNAL EDDY CURRENT INSPECTION INSTRUCTION FOR THE
EXAMINATION OF THE REAR FUSELAGE AFT SKIN LAP JOINTS.
1. PROCEDURE
A. GENERAL
(1)  This low frequency, phase analysis, external eddy current
inspection instruction has been produced to detect cracks in
the rear fuselage aft skin lap joints.
NOTE: At Revision 4 or later of this ISB, this inspection
procedure is only to be used to inspect the aft skin lap
joints at stringers 11 and 30, at the locations shown in
Drawing 1 and Drawing 2. This inspection procedure is
not to be used if there is a repair present.
B.COMPONENT OR AREA TO BE INSPECTED
The components to be inspected are the rear fuselage aft skin
lap joints at stringer 11 left and right up to 6 inches
forward of door frame, and stringer 30 left and right between
3.0 inches forward and 11.0 inches aft of frame 42 (see
Drawing 1 or Drawing 2).
NOTE: On large freight door aircraft, stringer 11 left is not
inspected.
C.DESCRIPTION OF POSSIBLE DAMAGE
(1)  Cracks 0.5 in. (12.7 mm.) or greater in length that lie 0.016
in. (0.41 mm.) or less below the surface of the skin panels
at the skin lands. It is anticipated that cracks will
originate in, and propagate along, the rebate which forms the
skin land.
D.RELATED DOCUMENTS
(1) NTM Part 1, Chapter 20-00-00, Section 3, Safety Precautions.
(2) NTM Part 6, Chapter 20-00-00, Eddy Current Testing - General.
(3) Aircraft Maintenance Manual (AMM).
(4) Test Instrument Manufacturer's Handbook.
Date: 13-JUN-2012  ISB. 53-239
Revision: 5 02-MAR-2017  Page 1 of 14
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 2
E.EQUIPMENT AND MATERIALS
(1)  The following equipment was used during the development of
this inspection instruction and was found acceptable.
Table 1.
(1)  Instrument  Elotest B1v4 phase analysis eddy current
instrument, with B1-RS adapter, from Rohmann
(UK) Ltd.
(2)  Probe  Absolute shielded probe with ferrite core,
300 Hz. - 100 kHz. Part number PKA 42-9E,
from Rohmann (UK) Ltd (Ref. Drawing 4,
appendix 2).
(3)  Lead  Part number EK-2-HF/1, from Rohmann (UK) Ltd.
(4)  Reference Standard  Locally manufactured.
Part number SORFIT 146/166/1 (Ref.Drawing 5
and Drawing 6, appendix 2).
(5)  Straight edge  Locally manufacture from suitable
non-conductive material such as plastic or
nylon.
NOTE:  Reference Standard SORFIT, 146/166 may be used for this
inspection provided SLOT A2 ONLY is used when setting
sensitivity. Slots A1, B1 and B2 were included for
development purposes and should not be used for this
inspection.
NOTE: Any comparable eddy current equipment may be used
provided it satisfies the requirements of this
instruction and is capable of resolving the slot in the
reference  standard at the required level of sensitivity.
F.PREPARATION FOR INSPECTION
(1) Aircraft.
(a) Ensure adequate staging/access platforms are in place to
provide safe access to the inspection areas.
(b) Remove dorsal panels 273CT, 275AT, 275BR and 275CR to
uncover lap joint at stringer 2.
(2) Component.
(a) Ensure scan surfaces are clean, smooth (flatten sealant if
protruding) and free from flaking paint.
Date: 13-JUN-2012  ISB. 53-239
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 2
(b) Check the inspection areas for any visible damage prior to
inspection.
G.INSTRUMENT CALIBRATION
(1)  Instrument settings.
Table 2.
Initial settings  Refer to manufacturer's instructions.
Alarm  Optional - refer to manufacturer's instructions.
Frequency  Inspection Frequency Set to 10 kHz.
Gain  Set to produce required sensitivity.
Pre-amp  O dB.
Y spread  20 dB.
X spread  O dB.
Filter:  Band  Set to Static.
High pass  Set to Off.
Low pass  Set to 10 Hz.
Bandwidth limiter  Set to Off.
Timebase/Display  Y/X.
Dot position  Reference Drawing 4, appendix 2.
(2) Sensitivity setting (Ref.Drawing 4, appendix 2).
(a) Place the probe on the reference standard away from the
sub-surface slot and balance the instrument.
(b) Set lift-off effect to horizontal and to the left.
(c) Slide the probe over the sub-surface slot and note the
response. Adjust the instrument settings to obtain a
display similar to that shown in Drawing 4, appendix 2.
Ensure that the slot produces a positive vertical spot
displacement of 50 percent of FSH.
Date: 13-JUN-2012  ISB. 53-239
Revision: 5 02-MAR-2017  Page 3 of 14
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 2
H.INSPECTION PROCEDURE
(Ref. Drawing 1 or Drawing 2, as appropriate, and Drawing 3,
appendix 2).
(1) Inspection method.
(a) Place the probe on the fuselage outer skin centrally over
the skin land gap and balance the instrument.
NOTE: Care should be taken when balancing the instrument.
The effect of balancing on a defect will cause the
slot to move more rapidly downwards when the end of
the crack has been reached. If in doubt, the balance
can be checked on a different skin land.
(b) Adjust lift-off as required.
(c) Scan along the skin land gap, using the straight edge to
keep the probe central and observe all signal responses.
(d) Scan the skin along the lands at the rear fuselage aft skin
lap joints at stringers 11, 18 and 30 left and right and
stringer 2 right.
I.ACCEPTANCE CRITERIA
(1) Interpretation.
(a) Cracks are indicated by a rapid vertical spot displacement
away from the balanced position (Ref.Drawing 4, appendix
2).
NOTE: Cracks and other discrete surface damage are usually
identified by a rapid positive vertical spot
displacement away from the balanced position.
However, once the crack or damage is passed the spot
returns to the balanced position.
NOTE:  Smooth, gradual spot movement is a common
occurrence, which happens for a variety of reasons
such as paint thickness variation (lift-off), edge
effect and conductivity changes.
(2) Accept/Reject criteria.
(a) Any indication with a rapid vertical spot displacement
equal to or greater than 20 percent of FSH height that
cannot be attributed to probe handling, fasteners or
component geometry shall be considered as a crack.
Date: 13-JUN-2012  ISB. 53-239
Revision: 5 02-MAR-2017  Page 4 of 14
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### Page 25 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 2
(3) Reporting/repair/rectification.
(a) All crack and discontinuity indications are to be recorded
in the relevant aircraft documentation and the appropriate
BAE SYSTEMS approved repair/rectification action taken.
NOTE: The word discontinuity is a generic term for faults
such as cracks, corrosion and mechanical damage.
J. REPORTING PROCEDURE
(1) Report all cracks/discontinuities to:-
Fleet Data Department (Building 37),
BAE SYSTEMS (Operations) Limited,
Prestwick International Airport,
Ayrshire,
Scotland,
KA9 2RW.
(2) Also send the following information:-
(a) Aircraft constructor's number.
(b) Aircraft registration.
(c) Flying hours and number of landings.
(d) ISB number.
(e) Location/ area  or length of the crack or
discontinuity/percent FSH.
K.ADDITIONAL INFORMATION
(1)  Ensure all test equipment is removed from the aircraft on
completion of work.
Date: 13-JUN-2012  ISB. 53-239
Revision: 5 02-MAR-2017  Page 5 of 14
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### Page 26 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 2
FRAME 42
AT STRINGER 11 LH & RH, UPTO
6.0 in. (152.4 mm) FORWARD OF
THE DOOR FRAME. AREA TO BE
FRAME 44  INSPECTED UNLESS THERE IS
A REPAIR PRESENT.
FRAME
42
FRAME 39Y  FRAME  FRAME
44  39Y
20|00000000  STR 11 RH
FRAME  _c
42
FRAME  FRAME
39Y  44
STR 30 RH
STR 11 LH  AT STRINGER 30 LH & RH,
BETWEEN 3.0 in. (76.2 mm) FORWARD TO 11.0 in (279.4 mm)
AFT OF FRAME 42. AREA TO BE INSPECTED UNLESS
THERE IS A REPAIR PRESENT.
• STR 30 LH
VIEW LOOKING INBOARD
RIGHT SIDE
VIEW LOOKING INBOARD
LEFT SIDE
LAP JOINT  STR 11 RH  „STR 11 LH
REPAIR  LAP JOINT
REPAIR
LAP JOINT
REPAIR  STR 30 RH  * STR 30 LH
LAP JOINT REPAIRS
TYPICAL
VIEW LOOKING AFT
IF THE REPAIR EXTENDS ACROSS THE
LAP JOINT, I.E. IT DOES NOT ABUT IT,
THEN NO INSPECTION IS REQUIRED.  N5323902
LOCATION OF INSPECTION AREAS, LEFT AND RIGHT - PASSENGER AIRCRAFT
DRAWING 1. (Revised)
Date: 13-JUN-2012  ISB. 53-239
Revision: 5 02-MAR-2017  Page 6 of 14
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### Page 27 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 2
AT STRINGER 11 RH, UPTO
FRAME 42  6.0 in. (152.4 mm) FORWARD
OF THE DOOR FRAME. AREA
TO BE INSPECTED UNLESS
THERE IS A REPAIR PRESENT.
FRAME
-FRAME 44  42
FRAME  FRAME
44  39Y
FRAME 39Y
STR 11 RH
_c
FRAME
42
FRAME  FRAME  STR 30 RH
39Y  44
AT STRINGER 30 LH & RH,
BETWEEN 3.0 in. (76.2 mm) FORWARD TO 11.0 in (279.4 mm)
AFT OF FRAME 42. AREA TO BE INSPECTED UNLESS
THERE IS A REPAIR PRESENT.
VIEW LOOKING INBOARD
RIGHT SIDE
- STR 30 LH
VIEW LOOKING INBOARD
LEFT SIDE
LAP JOINT  STR 11 RH.
REPAIR  LAP JOINT
REPAIR
LAP JOINT
REPAIR  STR 30 RH  *STR 30 LH
LAP JOINT REPAIRS
TYPICAL  C
NOTE:
VIEW LOOKING AFT
ON LARGE FREIGHT DOOR AIRCRAFT
STRINGER 11 LH FORWARD OF THE
DOOR DOES NOT REQUIRE INSPECTION.
IF THE REPAIR EXTENDS ACROSS THE
LAP JOINT, I.E. IT DOES NOT ABUT IT,  THEN NO INSPECTION IS REQUIRED.  B5323917
LOCATION OF INSPECTION AREAS, LEFT AND RIGHT - AIRCRAFT WITH LARGE
FREIGHT DOOR
DRAWING 2. (Revised)
Date: 13-JUN-2012  ISB. 53-239
Revision: 5 02-MAR-2017  Page 7 of 14
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### Page 28 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 2
EXPECT A SMALL INDICATION DUE TO FASTENERS
FALLING CLOSE TO THE SKIN LAND GAP
(THIS IS LIKELY AT CERTAIN FRAME POSITIONS)
LAP
JOINT
ETCHED
REBATE
PROBE  SECTION 'E-E'
STRAIGHT EDGE
FUSELAGE
SCAN ALONG THE SKIN  OUTER SKIN
LAND GAP USING THE
PROBE GUIDE
D
TYPICAL
STRINGER 30 SHOWN
N5323903
PROBE POSITIONING AND SCAN DETAILS
DRAWING 3.
Date: 13-JUN-2012  ISB. 53-239
Revision: 5 02-MAR-2017  Page 8 of 14
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 2
SIGNAL FROM SUB-SURFACE
SLOT - 50% F.S.H.
75% FSH
50% FSH
25% FSH
'X'INDICATES
BALANCE POSITION
LIFT OFF
TYPICAL ELOTEST B1 v4 SCREEN DISPLAY FOR
SUB-SURFACE SLOT IN REFERENCE STANDARD
PROBE IN
SUB-SURFACE
SLOT POSITION  PROBE IN
BALANCE POSITION
SORFIT 146/166/1
SUB-SURFACE
0.79in (20mm)  SLOT
42-95
err
PKA
42-9E
err
0.4in (10mm) DIA
PROBE FACE
MANUFACTURER:  ROHMANN (UK) LTD
TYPE:  ABSOLUTE FERRITE CORE (SHIELDED)
PART NUMBER:  PKA 42-9E
FREQUENCY RANGE:  300 Hz - 100 kHz
CONNECTOR:  FISCHER 4 PIN  N5323904
INSTRUMENT CALIBRATION AND PROBE DETAILS
DRAWING 4.
Date: 13-JUN-2012  ISB. 53-239
Revision: 5 02-MAR-2017  Page 9 of 14
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### Page 30 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 2
4.0in
(101.6mm)
1.00in
(25.4mm)
0.068in
(1.73mm)  G  G
2.50in
0.432in  (63.5mm)
(10.97mm)
0.50in
(12.7mm)
0.50in
(12.7mm)
SORFIT 146/166/1
0.50in  0.75in  0.50in  SECTION 'F-F'
(12.7mm)  (19.05mm)  (12.7mm)
PITCH
SECTION 'G-G'
1. INNER SKIN  2. OUTER SKIN  3. FASTENERS
BS L166  BS L166
0.126in (3.2mm)  0.058in (1.47mm)
MACHINED
RIVET
EQUIVALENT MATERIAL SPECIFICATION  4070-40-10
5 POSITIONS
INTERNATIONAL DESIGNATION
2014A-T4  2014A-T4
ALCLAD  ALCLAD
FOR FASTENER INFORMATION AND IDENTIFICATION REFER TO STRUCTURAL REPAIR MANUAL 51-41-00
FOR DRILLING AND COUNTERSINKING INFORMATION REFER TO STRUCTURAL REPAIR MANUAL 51-42-00.
UNLESS STATED OTHERWISE DIMENSIONAL TOLERANCE IS +/- 0.010in. (0.25mm).
THE APPLICATION OF SURFACE PROTECTION IS OPTIONAL.
THE REFERENCE STANDARD DOES NOT REQUIRE ANY JOINTING COMPOUNDS.
MARK REFERENCE NUMBER ON TOP SURFACE IN A PERMANENT MANNER.
N5323905
CALIBRATION STANDARD PART NUMBER SORFIT 146/166/1 - MATERIAL DETAILS
DRAWING 5.
Date: 13-JUN-2012  ISB. 53-239
Revision: 5 02-MAR-2017  Page 10 of 14
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 2
1.75in  0.50in  1.75in
(44.45mm)  (12.7mm)  (44.45mm)
н[>
C
1075
0. 126ir
3.2mm  0.016in
(0.41mm)
0.068 in
(1.73mm)
(1.47mm) →  0.058in  (1.73mm)  0.068 in
RAD  SLOT
SORFIT 146/166/1
ONE SLOT IN ITEM 1 = 0.5in (12.7mm) LONG
SLOT IS SUB-SURFACE
MAXIMUM SLOT WIDTH 0.010in (0.25mm)
NO SLOTS IN ITEM 2
DIMENSIONAL TOLERANCE +/-0.010in (0.25mm)
N5323906
CALIBRATION STANDARD PART NUMBER SORFIT 146/166/1 - SLOT DETAILS
DRAWING 6.
Date: 13-JUN-2012  ISB. 53-239
Revision: 5 02-MAR-2017  Page 11 of 14
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### Page 32 (OCR)

BAE SYSTEMS
BAe 146 SEPEES AVRO 146-CE SERLES AIRCRAFT
APPENDIX 2
2.ACCOMPLISHMENT INSTRUCTIONS
Not applicable.
ate: 13-JUN-2012  evision: 5 02-MAR-201  SB. 53-23
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### Page 33 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 2
3 MATERIAL INFORMATION
Not applicable.
ate: 13-JUN-2012  evision: 5 02-MAR-201  SB. 33-25  ade 150+1
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
This Page Is Intentionally Left Blank.
ate: 13-JUN-201  eV1s1on: 5 02-MAR-201  SB. 53-23  0de 1 4 0+"
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### Page 35 (OCR)

BAE SYSTEMS (Operations) Limited, Prestwick International Airport, Ayrshire,
KA9 2RW, Scotland.
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
TRANSMITTAL FOR INSPECTION SERVICE BULLETIN REVISION
SERVICE BULLETIN No.ISB.53-239  APPENDIX 3
DATE: 31-MAR-2016
TITLE: EXTERNAL EDDY CURRENT INSPECTION INSTRUCTION FOR THE
EXAMINATION OF  THE FUSELAGE SKIN PANELS ADJACENT TO STRINGERS
2, 11, 18 AND 30 BETWEEN FUSELAGE FRAME 39Y AND 44.
REVISION:  1  DATE: 02-MAR-2017
ACTIONS
(1)  Remove and discard Appendix at initial issue.
(2)  Insert Appendix at revision 1.
REASONS FOR REVISION
(1)  Area of inspection clarified (see para.1.B.(1) and
para.1.H. (1)).
(2)  Inspection areas clarified and view of typical repairs added
(see Drawing 1).
(3)  Drawing 1 View B text for stringer 11 and stringer 30 amended
to ¿¿AREA NOT TO BE INSPECTED UNLESS THERE IS A REPAIR
PRESENT".
(4)  Note deleted referring to aircraft with large freight door
(see Drawing 1).
(5)  "D' identifier added next to "LAP JOINT REPAIRS TYPICAL" (see
Drawing 1 and Drawing 2).
(6)  Text "----- LAP JOINT WHERE" deleted (see Drawing 1 and
Drawing 2).
(7)  Drawing 2 added for aircraft with large freight door.
Subsequent drawings re-numbered.
(8) Drawing 2 View B text for stringer 11 and stringer 30 amended
to 'AREA NOT TO BE INSPECTED UNLESS THERE IS A REPAIR
PRESENT".
INCORPORATION OF THIS REVISION DOES NOT REQUIRE INSPECTIONS
ADDITIONAL TO THOSE DONE AT PREVIOUS REVISIONS OF THIS
INSPECTION SERVICE BULLETIN.
Date: 31-MAR-2016  REVISION TRANSMITTAL SHEET
ISB.53-239
Revision: 1 02-MAR-2017  Page 1 of 2
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
TRANSMITTAL FOR INSPECTION SERVICE BULLETIN REVISION
SERVICE BULLETIN No.ISB.53-239
This Page Is Intentionally Left Blank.
Date: 31-MAR-2016  REVISION TRANSMITTAL SHEET
ISB.53-239
Revision: 1 02-MAR-2017  Page 2 of 2
Printed in England

### Page 37 (OCR)

BAE SYSTEMS (Operations) Limited, Prestwick International Airport, Ayrshire,
KA9 2RW, Scotland.
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 3
TITLE: EXTERNAL EDDY CURRENT INSPECTION INSTRUCTION FOR THE
EXAMINATION OF THE FUSELAGE SKIN PANELS ADJACENT TO STRINGERS
2, 11, 18 AND 30 BETWEEN FUSELAGE FRAME 39Y AND 44.
1. PROCEDURE
A. GENERAL
(1) This low frequency, phase analysis, eddy current inspection
instruction has been produced to detect cracks in the
fuselage skin panels between Frame 39Y and Frame 44.
B.COMPONENT OR AREA TO BE INSPECTED
(1)  The areas to be inspected are the skin lands adjacent to
stringer 2 right and stringers 11, 18 and 30 left and right.
Stringer 11 left and right up to 6 inches forward of door
frame and stringer 30 left and right between 3.0 inches
forward and 11.0 inches aft of frame 42 (see Drawing 1 or
Drawing 2) are not to be inspected unless there is a repair
present.
C.DESCRIPTION OF POSSIBLE DAMAGE
(1)  Through cracks 1.0 in. (25.4 mm) or greater in length in the
fuselage skin panels at the skin lands. It is anticipated
that cracks will originate in, and propagate along, the
etched rebate which forms the skin land.
D.RELATED DOCUMENTS
(1) NTM Part 1, Chapter 20-00-00, Section 3, Safety Precautions.
(2) NTM Part 6, Chapter 20-00-00, Eddy Current Testing - General.
(3) Aircraft Maintenance Manual (AMM).
(4) Test Instrument Manufacturer's Handbook.
E.EQUIPMENT AND MATERIALS
(1) The following equipment was used during the development of
this inspection instruction and was found acceptable.
Date: 31-MAR-2016  ISB.53-239
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### Page 38 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 3
Table 1.
(1)  Instrument  Elotest B1v4 phase analysis eddy current
instrument, with B1-RS adapter, from Rohmann
(UK) Ltd.
(2)  probe  Absolute ferrite core, driver/receiver probe
200 Hz. - 100 kHz. Part number (p/n) PKA
34-18, from Rohmann (UK) Ltd. (Ref. Drawing 4,
appendix 3).
(3)  Lead  p/n EK-2-HF/1, from Rohmann (UK) Ltd.
(4)  Calibration Standard  Locally manufactured.
p/n SORFIT 146/166/2 (Ref.Drawing 5, Drawing
6 and Drawing 7, appendix 3).
(5)  Straight edge  Locally manufacture from suitable
non-conductive material such as plastic or
nylon.
(6)  Optional Packer  Local manufacture from suitable
non-conductive material such as plastic or
nylon. Five off to suit repair patch
thickness.
NOTE: Any comparable eddy current equipment may be used
provided it satisfies the requirements of this
instruction and is capable of resolving the slot in the
reference standard at the required level of sensitivity.
F.PREPARATION FOR INSPECTION
(1) Aircraft.
(a) Ensure adequate staging/access platforms are in place to
provide safe access to the inspection areas.
(b) Remove dorsal panels 273CT, 275AT, 275BR and 275CR to
uncover lap joint at stringer 2.
(c) Release drip tray/diaphragm p/n HC535B0216 covering
stringer 2 at Frame 44.
(2) Component.
(a) Ensure scan surfaces are clean, smooth (flatten sealant if
protruding) and free from flaking paint.
(b) Check the inspection areas for any visible damage prior to
inspection.
Date: 31-MAR-2016  ISB.53-239
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### Page 39 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 3
G.INSTRUMENT CALIBRATION
(1)  Instrument settings.
Table 2.
Initial settings  Refer to manufacturer's instructions.
Alarm  Optional - refer to manufacturer's instructions.
Frequency  Set to:
No repair  10 kHz.
Repair patch, 0.048 in.  10 kHz.
(1.219 mm)
Repair patch, 0.064 in.  8 kHz.
(1.626 mm)
Repair patch, 0.080 in.  8 kHz.
(2.032 mm)
Repair patch, 0.096 in.  5 kHz.
(2.438 mm)
Repair patch, 0.128 in.  5 KHz.
(3.251 mm)
Gain  Set to produce required sensitivity.
Pre-amp  O dB.
Y spread  20 dB.
X spread  O dB.
Filter:  Band  Set to Static.
High pass  Set to Off.
Low pass  Set to 10 Hz.
Bandwidth limiter  Set to Off.
Timebase/Display  Y/X.
Dot position  Reference Drawing 4, appendix 3.
(2) Sensitivity setting (Ref.Table 2 and Drawing 4, appendix 3).
(a) Place the probe on the reference standard away from the
sub-surface slot and balance the instrument.
Date: 31-MAR-2016  ISB.53-239
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BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 3
(b) Set lift-off effect to horizontal and to the left. Add 20
dB. to help identify and set the lift-off signal. When
signal is set, remove the 20 dB.
(c) Slide the probe over the sub-surface slot (slot 1) and note
the response. Adjust the instrument settings to obtain a
display similar to that shown in Drawing 4, appendix 3.
Ensure that the slot produces a negative vertical spot
displacement of 60 percent of FSH (minimum).
(d) Aircraft with external repair patches fitted:
Select calibration plate which corresponds to the thickness
of the repair patch fitted to the aircraft and attach to
the reference standard.
(e) With reference to Table 2 and Drawing 4 in appendix 3,
repeat operations (a) to (c).
(f) Repeat operations (a) to (e) for all repair patch
thicknesses.
NOTE: Slot 2 is not to be used for calibration.  Use it to
identify the effect on the signal and to illustrate
the screen display when a crack occurs close to the
edge of a patch.
H.INSPECTION PROCEDURE
(1)  Inspection  method (Ref. Drawing 1, Drawing 2 and Drawing 3,
appendix 3).
(a) Calibrate the instrument as detailed in para.1.G.
(b) Place  the probe on the fuselage outer skin centrally over
the skin land gap and balance the instrument.
NOTE: Care should be taken when balancing the instrument.
The effect of balancing on a defect will cause the
slot to move more rapidly upwards when the end of
the crack has been reached. If in doubt, the balance
can be checked on a different skin land.
(c) Adjust lift-off as required.
(d) Scan along the skin land gap, using the straight edge to
keep the probe central and observe all signal responses.
(e) Scan the skin along the lands at stringer 2 right and
stringers 11, 18 and 30 left and right, between frame 39Y
and frame 44.
Date: 31-MAR-2016  ISB.53-239
Revision: 1 02-MAR-2017  Page 4 of 16
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### Page 41 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 3
NOTE: Stringer 2 - Interruptions to the scan will occur at
the spine panel attachment brackets. In addition,
access difficulties will be encountered just forward
of frame 44. Taping a pencil or other non-conductive
extension to the probe will help in this area.
I ACCEPTANCE CRITERIA
(1) Interpretation.
(a) Cracks are indicated by a rapid vertical spot displacement
away from the balanced position (Ref. Drawing 4, appendix
3) _
NOTE: Cracks and other discrete surface damage  are usually
identified by a rapid negative vertical spot
displacement away from the balanced position.
However, once the  crack or damage is passed the spot
returns to the balanced position.
NOTE: Smooth, gradual spot movement is a common
occurrence, which happens for a variety of
such as paint thickness variation (lift-off), edge
effect and conductivity changes.
(2) Accept/Reject criteria.
(a) Any indication with a rapid negative vertical spot
displacement equal to or greater than 20 percent of FSH
height that cannot be attributed to probe handling,
fasteners or component geometry shall be considered as a
crack.
(3) Reporting/repair/rectification.
(a) All crack and discontinuity indications are to be recorded
in the relevant aircraft documentation and the appropriate
BAE SYSTEMS approved repair/rectification action taken.
NOTE: The word discontinuity is a generic term for faults
such as cracks, corrosion and mechanical damage.
J.REPORTING PROCEDURE
(1) Report all cracks/discontinuities to:-
Fleet Data Department (Building 37),
BAE SYSTEMS (Operations) Limited,
Prestwick International Airport,
Ayrshire,
Date: 31-MAR-2016  ISB.53-239
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### Page 42 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 3
Scotland,
KA9 2RW.
(2) Also send the following information:-
(a) Aircraft constructor's number.
(b) Aircraft registration.
(c) Flying hours and number of landings.
(d) ISB number.
(e) Location/area or length of the crack or
discontinuity/percent FSH.
K.ADDITIONAL INFORMATION
(1) Ensure all test equipment is removed from the aircraft on
completion of work.
Date: 31-MAR-2016  ISB.53-239
Revision: 1 02-MAR-2017  Page 6 of 16
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### Page 43 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 3
FRAME 42
AT STRINGER 11 LH & RH, UPTO
6.0 in. (152.4 mm) FORWARD OF
THE DOOR FRAME. AREA NOT TO
FRAME 44  BE INSPECTED UNLESS THERE IS
A REPAIR PRESENT.
FRAME
42
FRAME 39Y  FRAME  44  FRAME  39Y
00000000  STR 11 RH
FRAME  IC
42
FRAME  FRAME
39Y  44
STR 30 RH
STR 11 LH  AT STRINGER 30 LH & RH,
BETWEEN 3.0 in. (76.2 mm) FORWARD TO 11.0 in (279.4 mm)
AFT OF FRAME 42. AREA NOT TO BE INSPECTED UNLESS
THERE IS A REPAIR PRESENT.
• STR 30 LH
VIEW LOOKING INBOARD
RIGHT SIDE
VIEW LOOKING INBOARD
LEFT SIDE
LAP JOINT  STR 11 RH  _ STR 11 LH
REPAIR  LAP JOINT
REPAIR
LAP JOINT
REPAIR  STR 30 RH  * STR 30 LH
LAP JOINT REPAIRS  TYPICAL  c
VIEW LOOKING AFT
> IF THE REPAIR EXTENDS ACROSS THE
LAP JOINT, I.E. IT DOES NOT ABUT IT,
THEN NO INSPECTION IS REQUIRED  B5323918
LOCATION OF INSPECTION  AREAS, LEFT AND RIGHT - PASSENGER AIRCRAFT
DRAWING 1. (Revised)
Date: 31-MAR-2016  ISB.53-239
Revision: 1 02-MAR-2017  Page 7 of 16
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### Page 44 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 3
AT STRINGER 11 RH, UPTO
FRAME 42  6.0 in. (152.4 mm) FORWARD
OF THE DOOR FRAME, AREA
NOT TO BE INSPECTED UNLESS
THERE IS A REPAIR PRESENT,
FRAME
FRAME 44  42
FRAME  FRAME
44  39Y
FRAME 39Y
STR 11 RH
FRAME
42
FRAME  FRAME  STR 30 RH
39Y  44
AT STRINGER 30 LH & RH,
BETWEEN 3.0 in. (76.2 mm) FORWARD TO 11.0 in (279.4 mm)
AFT OF FRAME 42. AREA NOT TO BE INSPECTED UNLESS
THERE IS A REPAIR PRESENT.
VIEW LOOKING INBOARD
RIGHT SIDE
- STR 30 LH
VIEW LOOKING INBOARD
LEFT SIDE
STR 11 RH
LAP JOINT
REPAIR  LAP JOINT
REPAIR  LAP JOINT
REPAIR  STR 30 RH  * STR 30 LH
LAP JOINT REPAIRS
TYPICAL
NOTE:
VIEW LOOKING AFT
ON LARGE FREIGHT DOOR AIRCRAFT
STRINGER 11 LH FORWARD OF THE
DOOR DOES NOT REQUIRE INSPECTION.
IF THE REPAIR EXTENDS ACROSS THE
LAP JOINT, I.E. IT DOES NOT ABUT IT,
THEN NO INSPECTION IS REQUIRED.  N5323907
LOCATION OF INSPECTION AREAS, LEFT AND RIGHT - AIRCRAFT WITH LARGE
FREIGHT DOOR
DRAWING 2. (Revised)
Date: 31-MAR-2016  ISB.53-239
Revision: 1 02-MAR-2017  Page 8 of 16
Printed in England

### Page 45 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 3
EXPECT A SMALL INDICATION FROM ANY FASTENERS
FALLING CLOSE TO THE SKIN LAND GAP
(THIS IS LIKELY AT CERTAIN FRAME POSITIONS)
LAP
JOINT
PROBE
SKIN
LAND
GAP
SECTION 'E-E'
PROBE  STRAIGHT EDGE
FUSELAGE
SCAN ALONG THE SKIN  OUTER SKIN
LAND GAP USING THE
STRAIGHT EDGE AS A
PROBE GUIDE
D
TYPICAL
STRINGER 30 SHOWN
N5323910
PROBE POSITIONING AND SCAN DETAILS
DRAWING 3.
Date: 31-MAR-2016  ISB.53-239
Revision: 1 02-MAR-2017  Page 9 of 16
Printed in England

### Page 46 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 3
LIFT OFF
75% FSH
50% FSH
25% FSH
*' INDICATES
BALANCE POSITION
SIGNAL FROM
SUB-SURFACE SLOT
MINIMUM 60% FSH
TYPICAL ELOTEST B1 v4 SCREEN DISPLAY FOR
SUB-SURFACE SLOT IN REFERENCE STANDARD
SLOT 1
SLOT 2  REPAIR  (CALIBRATION)  BALANCE
POSITION  PATCH  POSITION  POSITION  F
SORFIT 146/166/2  SORFIT 146/166/2  0.048
STRAIGHT EDGE  TYPICAL
OPTIONAL
SPACER
e  PKA 34-18
2.17 in. (55.0 mm)
SELECT
APPROPRIATE
THICKNESS
REPAIR PATCH
ABSOLUTE FERRITE CORE
NO REPAIR  WITH REPAIR  PART No PKA 34-18
DRIVER/RECEIVER
SECTION 'F-F'  200 Hz. - 100 kHz.
OPEN HOLES  0.787 in.
N5323911
(20.0 mm)
INSTRUMENT CALIBRATION AND PROBE DETAILS
DRAWING 4.
Date: 31-MAR-2016  ISB.53-239
Revision: 1 02-MAR-2017  Page 10 of 16
Printed in England

### Page 47 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 3
G  FOR FASTENER INFORMATION AND IDENTIFICATION REFER TO  STRUCTURAL REPAIR MANUAL 51-41-00.  FOR DRILLING AND COUNTERSINKING INFORMATION REFER TO  STRUCTURAL REPAIR MANUAL 51-42-00  UNLESS STATED OTHERWISE DIMENSIONAL TOLERANCE IS  UNLESS STATED OTHERWISE EQUIVALENT AIRCRAFT GRADE  MATERIAL MAY BE SUBSTITUTED PROVIDED THE CONDUCTIVITY  (IACS) IS +/- 5 PERCENT OF THE MATERIAL SPECIFIED.  THE APPLICATION OF SURFACE PROTECTION IS OPTIONAL.  THE REFERENCE STANDARD DOES NOT REQUIRE ANY JOINTING  MARK REFERENCE NUMBER ON TOP SURFACE IN A PERMANENT
+/- 0.010 in. (0.25 mm).  COMPOUNDS.  MANNER.
12.0 in. (304.80 mm)  SECTION 'H-H"  3. FASTENERS  RIVET  NAS1097 AD 5-7  13 POSITIONS
2. OUTER SKIN  BS L166  0.058 in. (1.47 mm)  EQUIVALENT MATERIAL SPECIFICATION  INTERNATIONAL DESIGNATION  2014A-T4  ALCLAD
1. INNER SKIN  BS L166  0.126 in. (3.2 mm)  MACHINED  2014A-T4  ALCLAD
OPEN HOLES  SORFIT 146/166/2  0.75 in.  (19.05 mm)  PITCH  SECTION  G-G'
N5323912
CALIBRATION STANDARD P/N SORFIT 146/166/2 - MATERIAL DETAILS
DRAWING 5.
Date: 31-MAR-2016  ISB.53-239
Revision: 1 02-MAR-2017  Page 11 of 16
Printed in England

### Page 48 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 3
TYPICAL
REPAIR PATCH -
30 DEG.
• MIN.
0.01 in.
(0.254 mm)
CHAMFER DETAILS
SECTION 'G-G'
SHOWING REPAIR PATCH
IN POSITION
RAD.
0.432 in.
(10.97 mm)
(36.37 mm)  0.432 in.  0.432 in.
(10.97 mm)  (10.97 mm)
SORFIT 146/166/2  0.048
10.50 in. (266.70 mm)
4. REPAIR PATCH  5. REPAIR PATCHES REQUIRED
ALL MADE USING THE SAME DIMENSIONS AND MATERIAL
BS L166  BUT WITH THICKNESS VARIATIONS AS FOLLOWS:-
1 OFF 0.048 in. (1.219 mm) THICK
1 OFF 0.064 in. (1.626 mm) THICK.
EQUIVALENT MATERIAL SPECIFICATION  INTERNATIONAL DESIGNATION  1 OFF 0.080 in. (2.032 mm) THICK.  1 OFF 0.096 in. (2.438 mm) THICK
1 OFF 0.128 in. (3.251 mm) THICK
2014A-T4 ALCLAD  MARK THICKNESS ON FACE OF PATCH.
N5323913
CALIBRATION STANDARD P/N SORFIT 146/166/2 - MATERIAL DETAILS
DRAWING 6.
Date: 31-MAR-2016  ISB.53-239
Revision: 1 02-MAR-2017  Page 12 of 16
Printed in England

### Page 49 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 3
0.50 in.
(12.7 mm)
1.00 in.  4.00 in. (101.6 mm)  1.00 in.
(25.4 mm) |  (25.4 mm)
SLOT 2  SLOT 1  ITEM 1
0.126 in.
(3.2 mm)
THROUGH
SLOT
0.068 in.
(1.73 mm)
0.058 in.  0.068 in.
(1.47 mm)  (1.73 mm)
RAD.
SORFIT 146/166/2
ITEM 2
SORFIT 148/166/2  0,048
KEY:-  ITEM 4
TWO SLOTS IN ITEM 1.  TYPICAL
SLOTS 1 AND 2 ARE THROUGH THICKNESS.
MAXIMUM SLOT WIDTH 0.010 in. (0.25 mm).
NO SLOTS IN ITEMS 2 OR 4.
• HOLES IN ITEM 4 TO PICK UP ON HOLES IN ITEMS 1 AND 2
AS INDICATED. HOLES TO BE LEFT OPEN AND APPROPRIATE
DIAMETER FASTENERS PROVIDED TO ALLOW REPAIR PATCHES
TO BE CHANGED AS REQUIRED.
DIMENSIONAL TOLERANCE IS +/- 0.010 in. (0.25 mm).  N5323914
CALIBRATION STANDARD P/N SORFIT 146/166/2 - SLOT DETAILS
DRAWING 7.
Date: 31-MAR-2016  ISB.53-239
Revision: 1 02-MAR-2017  Page 13 of 16
Printed in England

### Page 50 (OCR)

BAE SYSTEMS
BAe 146 SEPEES AVRO 146-CE SERLES AIRCRAFT
APPENDIX 3
2.ACCOMPLISHMENT INSTRUCTIONS
Not applicable.
ate: 31-MAR-2016  evision: 1 02-MAR-201  0de 140+"
Printed in England

### Page 51 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
APPENDIX 3
3 MATERIAL INFORMATION
Not applicable.
ate: 31-MAR-2016  evision: 1 U2-MAR-2U1  SB. 33-23
Printed in England

### Page 52 (OCR)

BAE SYSTEMS
INSPECTION SERVICE BULLETIN
BAe 146 SERIES/AVRO 146-RJ SERIES AIRCRAFT
This Page Is Intentionally Left Blank.
ate: 31-MAR-201  eV1s1on: 1 U2-MAR-201  SB .33-2-
Printed in England

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