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SUBJECT: ATA 57 – INSPECT LH AND RH BOTTOM SKIN FASTENERS AT MAIN LANDING GEAR 

RIB 5 FOOTPRINT LOCATION FOR MIGRATED OR MISSING FASTENER

AIRCRAFT TYPE: A319,A320

OUR REF.: A57N006-14 Rev 01 dated 16 Feb 2015.

0. REASON FOR REVISION

The revision 01 of this AOT is required to extend the inspection interval from 8 days to 60 days for the 

external area and for the internal inboard side. The 120 days repetitive inspection remains for the 

internal outboard area. A318 references have been removed since none of these aircraft type has 

been manufactured with the suspected batch of fasteners. Inspection flow charts have been modified 

to reflect the new intervals and clarify the sequence of actions. Spare parts numbers have been 

clarified. 

The revised paragraphs are indicated between **BEG. REV** and **END REV**.

1. AIRCRAFT AFFECTED

**BEG. REV**

Applicable to MSN 5817, 5826, 5837, 5848, 5855, 5864, 5875, 5886, 5896, 5910 and all A319 and 

A320 Aircraft delivered from MSN 5918 onwards.

**END REV**

2. REFERENCED DOCUMENTATION

2.1 APPENDIX

AOT A57N006-14 Appendix A: decision tree for the external inspection.

AOT A57N006-14 Appendix B: decision tree for the internal inspection.

AOT A57N006-14 Appendix C: reporting sheet.

2.2 REFERENCES

All limitations provided with concession suffix R related to this topic issued on delivered aircraft since 

November 2014 are superseded by this AOT.

**BEG. REV**

Ref. A: SRM 51-42-11 Paragraph 9

Ref. B: AMM 57-51-37-000-008 Removal of the Access Door

Ref. C: AMM 57-51-37-400-008 Installation of the Access Door

Ref. D: AMM 51-78-00-615-005 Removal of Corrosion Preventive Compound

Ref. E: AMM 51-78-00-916-001 Application of Temporary Protection System (TPS)

Ref. F: TFU 57.21.00.012 latest issue.

Ref. G: EASA AD 2014-0270 & FAA AD 2014-26-53.

**END REV**
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3. REASON

Inspection of Taperlok fasteners on A320 Family aircraft, located in the joint between the Main 

Landing Gear Support Rib lower flanges & lower wing skins on LH & RH wings, is required to ensure 

continued airworthiness. The inspection program is aimed at detecting Taperloks that have failed.

3.1 FACTS

During production of A319, A320 wings a number of taperlok fasteners have been found failed after 

installation. Initial investigations highlight an issue with taperlok fasteners. The fasteners in question 

are located at the bottom skin of the MLG reinforcing plate, wing skin and Gear Support Rib 5 lower 

flange (refer to fig. 1, 2 and 3). 

**BEG. REV**

The taperlok fasteners are installed on A319 & A320 aircraft wings. A318 aircraft are NOT affected as 

no wing assembly have used fasteners coming from suspected batches. A321 aircraft are NOT 

affected as wing assembly is done using parallel shank fasteners. 

**END REV**

Figure 1- Location of affected fasteners/ External 

Affected Area
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Fig. 2 view of inboard (looking outboard) of MLG rib 5 / Internal 

Fig. 3 view of outboard (looking inboard) of MLG rib 5 /Internal 

Area to be 

inspected

Area to be 

inspected

Area to be 

inspected
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**BEG. REV**

Figure 4a- Location of affected fasteners heads, lower wing skin view looking up

Figure 4b- Location of affected fasteners nuts/bolt tails, MLG support rib bottom flange upper 

surface, view looking down

Outboard Inboard

All fasteners nuts/bolt tails 

identified on the outboard to 

be inspected on a 120 days

basis

All fasteners nuts/ bolt tails 

identified on the inboard to 

be inspected on a 60 days

basis

All fasteners heads identified as to be inspected on a 60 days basis

FORWARD

OUTBOARD

Gear support rib installation D572-52180

LH shown – RH symmetrical

Gear support rib installation D572-52180

LH shown – RH symmetrical

Gear rib 5 web axis

Inboard Outboard

External 

Internal

FORWARD

OUTBOARD
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**END REV**

3.2 CONSEQUENCES

Failure of these fasteners may results in a reduction in the design margin of the structure.

**BEG. REV**

3.3 AIM

The aim of this AOT is to ensure that taperlok fasteners, affected by the failure mode, are identified 

and replaced in order to restore the design margin.

Affected aircraft operators have to perform a Detail Visual Inspection (DVI) of the external surface of 

the LH and RH lower wing surface for migrating or missing fasteners and of the internal side of the 

MLG support rib lower flange for broken fastener tails/nuts (refer to fig. 4a and 4b).

4. SHORT TERM ACTION

For the external inspection:

 Visually inspect inboard/outboard fastener head.

For the internal inspection:

 Visually inspect inboard /outboard fastener nut/bolt tail.

NOTE:

- In the event of no more than 1 fastener missing per side, the affected fastener needs to be replaced

within 120 days as per Ref. A. 

- In case of more than one fastener missing per side, the operator has to replace affected fasteners 

before next flight leaving no more than 1 missing fastener.

For both inspection areas, even after fastener replacement, the inspection described in this AOT has 

to be performed at the same intervals until further notice.
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4.1 PLANNING AND MANPOWER

4.1.1 ACCOMPLISHMENT TIMESCALE

For the external inspection:

THRESHOLD: No later than 60 days from last inspection as per AD Ref. G or since entry into service.

GRACE PERIOD: N/A

INTERVAL: No later than 60 days. 

For the internal inspection:

 Inboard:

THRESHOLD: No later than 60 days from last inspection as per AD Ref. G or since entry into service.

GRACE PERIOD: N/A

INTERVAL: No later than 60 days. 

 Outboard:

THRESHOLD: No later than 120 days from last inspection or from AD Ref. G first issuance whichever 

occurs later or 120 days since entry into service.

GRACE PERIOD: N/A

INTERVAL: No later than 120 days.

Note: - For the 60 days inspection refer to Appendix A

 - For the 120 days inspection refer to Appendix B

4.1.2 MANPOWER

The estimated amount of man hours to perform the DVIs every 60 days is1 hour per aircraft, both 

sides included.

The estimated amount of man hours to perform the DVIs every 120 days is 2 hours per aircraft, both 

sides included.

**END. REV**

4.2 DESCRIPTION
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4.2.1 ACCESS

**BEG. REV**

For the 60 days inspection:

Support Equipment for access: 

• Access platform 2M (6 FT) adjustable, 

• Safety harness.

Put an ACCESS PLATFORM 2M (6 FT) in position. The use of magnifying tools may be required.

For the 120 days inspection:

Support Equipment for access: 

• Access platform 2M (6 FT) adjustable, 

• Safety harness. 

**END REV**

Work Zone and Access Panel: 

• Access Panel 574AB & 674AB (Door entrance of false rear spar area), 

• Warning & safety precautions:

WARNING:MAKE SURE THAT THE GROUND SAFETY-LOCKS ARE IN POSITION ON THE 

LANDING GEAR. 

WARNING:PUT THE SAFETY DEVICES AND THE WARNING NOTICES IN POSITION BEFORE 

YOU START A TASK ON OR NEAR: 

- THE FLIGHT CONTROLS 

- THE FLIGHT CONTROL SURFACES 

- THE LANDING GEAR AND THE RELATED DOORS 

- COMPONENTS THAT MOVE. 

MOVEMENT OF COMPONENTS CAN KILL OR CAUSE INJURY TO PERSONS 

AND/OR CAN CAUSE DAMAGE TO THE EQUIPMENT. 

CAUTION:BE CAREFUL WHEN YOU DO MAINTENANCE TASKS ON THE WING TRAILING 

EDGE: 

- DO NOT CAUSE DAMAGE TO THE ELECTRICAL CABLE RACEWAYS. 

- DO NOT CAUSE DAMAGE TO THE ELECTRICAL CABLE INSTALLATIONS. 

-

 

MAKE SURE THAT THE ELECTRICAL CABLES ARE INSTALLED CORRECTLY. 

INCORRECT INSTALLATION CAN CAUSE DAMAGE. 

Put an ACCESS PLATFORM 2M (6 FT) in position. The use of magnifying tools may be required.

Perform access as per Ref. B and C.

4.2.2 INSPECTION REQUIREMENTS

Do a DVI of the external surface of the LH an RH bottom skin lower wing surface for migrated or 

missing fasteners.

Do a DVI of the INBOARD/OUTBOARD MLG Support Rib lower flange fasteners and nuts for missing 

nuts / tails.

For typical findings refer to Fig 5a and 5b.
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Fig. 5a example of finding (migration)

Fig. 5b example of finding (nut/tail missing on inboard area)
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4.2.3 FINDINGS

Failed fasteners (broken, migrated, missing)

Failed tail/nut (broken, missing)

In case of finding, refer to Appendix A and B.

**BEG. REV**

If a failed fastener has to be removed the following instructions are to be followed:

 Mark the orientation of the fastener on the head (i.e. inboard/outboard).

 Mark the location of the fastener on bolting diagram as per Appendix C.

 Get access to the area.

 Remove affected fastener.

 All effort should be made not to damage the fracture surface of the fastener during removal.

 The fastener and associated nut/tail is to be returned to Airbus.

 Report all findings to Airbus as per Appendix C.

Refer to TFU Ref. F for additional guidance for access and fastener replacement.

4.3 SPARES AND TOOLING

In case of finding, for fastener replacement Airbus recommends to order the following:

- Nominal part number.

- First oversize (as precautionary measure).

- Associated nut.

- Washers part number (both thickness).

- Reamer & installation tooling (as precautionary measure)

FORWARD

OUTBOARD

LH shown – RH symmetrical

Gear support rib installation D572-52180
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Fig. 6 Identification and location of fasteners at rib 5 attachment.

Fasteners part numbers:

fastener 

identification as 

per Fig 7

Nominal 1st Oversize

42 NSA5486-9-25N NSA5487-9-25N

41 NSA5486-9-26N NSA5487-9-26N

8-40-43 NSA5486-9-27N NSA5487-9-27N

2-37-38-39-44-45 NSA5486-9-28N NSA5487-9-28N

1-18-36 NSA5486-9-29N NSA5487-9-29N

9-17-19-26-27 NSA5486-9-30N NSA5487-9-30N

10 NSA5486-9-31N NSA5487-9-31N

11-23 NSA5486-9-32N NSA5487-9-32N

21 NSA5486-9-33N NSA5487-9-33N

7 NSA5486-9-34N NSA5487-9-34N

46 NSA5486-10-22N NSA5487-10-22N

29-30-31-32 NSA5486-10-28N NSA5487-10-28N

28 NSA5486-10-29N NSA5487-10-29N

4-5-6-20-33-34-35 NSA5486-10-30N NSA5487-10-30N

3-15-25 NSA5486-10-31N NSA5487-10-31N

13-14-22-24 NSA5486-10-32N NSA5487-10-32N

12 NSA5486-10-33N NSA5487-10-33N

16 NSA5486-10-35N NSA5487-10-35N

Nuts part numbers:

NSA5472-9K7

NSA5472-10K7
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Washers part numbers:

NSA5372-1016AX

NSA5372-1016BX

NSA5372-916AX

NSA5372-916BX

NOTE:

-1016: washer diameter -10

-916: washer diameter -9

AX: washer thickness of 0,8mm

BX: washer thickness of 1,6mm

Installation tool in case of oversize: 

SOA57N00614

Reporting sheets appendix C to be sent to Airbus AOG spares (e-mail: aog.spares@airbus.com) 

with corresponding findings and purchase order.

5. FURTHER INFORMATION

5.1 FOLLOW-UP PLAN

This repeat inspection is to be continued until Airbus has defined a terminating action to this AOT. 

Pending the level of finding this AOT may be revised to refine its instructions.

Refer to TFU Ref. F. for follow up.

5.2 IMPACTED DOCUMENTATION

N/A
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6. AOT APPROVAL

The technical content of this document is approved under the authority of DOA nr. EASA.21J.031.

This AOT is mandated by the issuance of an EASA Airworthiness Directive Ref. G.

**END REV**

7. REPORTING

Questions about this AOT should be sent to the SEES2 department via the on-line TechRequest tool.

Inspection results with findings are to be sent (ref AOT A57N006-14 Appendix C) to Airbus Customer 

Services engineering as soon as possible, after the AOT application, to the attention of:

Julie BLANCHOT

Structure Engineer

Structure Engineering – SEES2 

CUSTOMER SERVICES

Phone: +33(0)5 61 93 60 20

Fax: +33 (0)5 61 93 36 14

Mailto: julie.blanchot@airbus.com

Ludovic MENARD

Outer Wing Product Leader

Structure Engineering – SEES2 

CUSTOMER SERVICES

Phone: +33(0)5 67 19 16 36

Fax: +33 (0)5 61 93 36 14

Mailto: Ludovic.menard@airbus.com

Best Regards,

Jean-Luc MOUYSSET

VICE PRESIDENT ENGINEERING SUPPORT

CUSTOMER SERVICES

Gilles DE CEVINS

VICE PRESIDENT A320 PROGRAMME

CUSTOMER SERVICES
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**BEG. REV**

AOT A57N006-14 Appendix A: decision tree for the 60 days inspection.

Inspection of the fastener heads in blue areas.

Inspection of nuts/bolt tails on blue area

View on Gear Rib to Lower Wing Cover, looking up

View on Gear Rib to Lower Wing Cover, looking down

External 

FORWARD

OUTBOARD

Internal

LH shown – RH symmetrical

LH shown – RH symmetrical

FORWARD

OUTBOARD
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AOT A57N006-14 Appendix A: decision tree for the 60 days inspection

For notes refer to page 17.
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AOT A57N006-14 Appendix B: decision tree for the internal 120 days inspection

View on Gear Rib to Lower Wing Cover, looking down

Inspection of nuts/bolt tails on red area

Internal

LH shown – RH symmetrical

FORWARD

OUTBOARD
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AOT A57N006-14 Appendix B: decision tree for the internal 120 days inspection

For notes refer to page 17.
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NOTES: 

a) Protect bore as per the following:

i. Apply TPS on open hole.

ii. Apply speed tape on fastener head side: 1 layer of speed tape over the 

affected location and 1 more layer overlapping it at 90°.

iii. Apply speed tape on bolt tail/nut side.

iv. On a 60 days basis replace speed tape on fastener head side only and 

re-apply TPS.

b) re-install fastener as per the following:

i. Re-install the fastener as per Ref. A within 120 days.

c) Apply speed tape as per the following:

i. For inboard findings:

i. Apply speed tape on fastener head side: 1 layer of speed tape 

over the affected location and 1 more layer overlapping it at 

90°.

ii. Apply speed tape on bolt tail/nut side.

iii. On a 30 days basis replace speed tape on fastener head side 

only.

ii. For outboard findings:

i. Apply speed tape on fastener head side: 1 layer of speed tape 

over the affected location and 1 more layer overlapping it at 

90°.

ii. On a 30 days basis replace speed tape on fastener head side 

only.

d) Airbus recommends to check high speed tape condition and replace 

accordingly.

**END REV**
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AOT A57N006-14 Appendix C: reporting sheet

AOT 57N006-14 REPORTING SHEET

A/C MSN

OPERATOR

FLIGHT CYCLES

FLIGHT HOURS

DATE OF LAST INSPECTION

NUMBER OF CONSECUTIVES INSPECTIONS
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AOT A57N006-14 Appendix C: reporting sheet

Expected date of failed part expedition:_______________

RETURN TO:

Julie BLANCHOT Ludovic MENARD

julie.blanchot@airbus.com ludovic.menard@airbus.com

TEL +33 (0)5 61 93 60 20 TEL +33 (0)5 67 19 16 36

FAX +33 (0)5 61 93 36 14 FAX +33 (0)5 61 93 36 14

AIRBUS

CUSTOMER SERVICES ENGINEERING-SEES2

WING -PYLON- STABILIZER

1 rond point Maurice Bellonte

31707 BLAGNAC CEDEX

France

Fastener 

Number LH side RH side Missing Fastener

Migrated 

Fastener

Nut / Tail 

missing