Visually Examine the Fan Cowls - Allowable Damage Data [IAE]

TASK 71-13-00-200-011-A
Visually Examine the Fan Cowls - Allowable Damage Data

1. Reason for the Job
This TASK gives the procedure for the inspection of the fan cowls to determine allowable damage.
General
Allowable damage data are intended to permit an operator to determine whether a damaged nacelle component may be returned to service without repair. Damage permitted by these data will have no significant effect on the strength or fatigue life of the structure, which will still be able to fulfill its design function. The types of allowable damage permitted are defined and brief descriptions are given of the cleanup procedures needed to either prevent damage propagation or improve the aerodynamic smoothness of the damaged part.
Material Types - The material used in the construction of the fan cowl doors are graphite composites, machined corrosion resistant (CRES) bar, aluminium alloy castings, molded silicon rubber sections and various fittings made from CRES sheet and forged steel alloys. The main structure of the fan cowl doors is a sandwich of graphite composite, two to seven plies thick, and aluminium alloy honeycomb of two different densities.
Damage
All damage limits assume that exposed edges do not extend above the skin contour. Any such damage should be reworked to remove or feather the extensions. Holes and cracks in the pressure boundaries must be sealed with applicable tape material. Allowable damage is classified as either unlimited usage or time limited.

Unlimited usage damage is defined as minor damage which does not affect the structural integrity or functional capability of the component and which needs no repairs over the aircraft design life.
Time limited damage is defined as minor damage which does not affect the structural integrity of the component in normal operation, but could reduce the design life of the component. Therefore, damage must be permanently repaired before or at 6000 flight hours/4500 flight cycles/20 months. The location and size of the damage is to be noted and checked at 600 flight hours, 750 flight cycles or 100 days intervals to make sure that the damage has not grown beyond the time limited damage allowances.

Damage Types
The types of allowable damage permitted on the fan cowl components are defined below. They apply only to the parent material and do not include damage to surface finishes such as paint.

Abrasion - An abrasion is a damage area which results in a cross sectional area change because the area was scuffed, rubbed, scraped or had other surface erosion. An abrasion usually appears rough and irregular.
Gouge - A gouge is a damage area of any size which results in a cross sectional area change. It is usually caused by contact with a relatively sharp object which produces a continuous, sharp or smooth channel-like groove in the material.
Nick - A nick is a local gouge with sharp edges. Consider a series of nicks in a line to be a gouge.
Scratch - A scratch is a line of damage in the material and results in a cross sectional area change. It is usually caused by contact with a very sharp object.
Crack - A crack is a partial fracture or complete break in the material and produces a most significant cross sectional area change. It usually appears as an irregular line.
Dent - A dent is a damage area which is depressed with respect to its normal contour. Area boundaries are smooth. Its form is usually the result of contact with a smoothly contoured object.
Hole - A hole is a complete penetration of the material.
Disbond - A disbond is a separation of the face sheet from the honeycomb core of a bonded panel.
Delamination - A delamination is the separation of two laminate plies or faying surfaces.

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	ACCESS PLATFORM 2M (6 FT)
No specific	AR	WARNING NOTICE(S)

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
FOR [1000EM1] (ENGINE-1)
437AL, 438AR
FOR [1000EM2] (ENGINE-2)
447AL, 448AR

C. Referenced Information

REFERENCE	DESIGNATION
TASK 71-13-00-010-010-A	Opening of the Fan Cowls 437AL(447AL),438AR(448AR)
TASK 71-13-00-410-010-A	Closing of the Fan Cowls 437AL(447AL),438AR(448AR)
NSRM 542000
Left Fan Cowl - Outer Skin
Left Fan Cowl - Inner Skin
Right Fan Cowl - Outer Skin
Right Fan Cowl - Inner Skin

3. Job Set-up
Subtask 71-13-00-941-059-A ** ON A/C NOT FOR ALL

A. Safety Precautions
(1) On the center pedestal, on the ENG panel 115VU:
(a) Put a WARNING NOTICE(S) to tell persons not to start the engine.
(2) Make sure that the engine 1(2) shutdown occurred not less than 5 minutes before you do this procedure.
(3) On the overhead maintenance panel 50VU:
(a) Make sure that the ON legend of the ENG/FADEC GND PWR/1(2) pushbutton switch is off.
(b) Put a WARNING NOTICE(S) to tell persons not to energize the FADEC 1(2).

Subtask 71-13-00-010-061-A ** ON A/C NOT FOR ALL

B. Get Access
(1) Open the fan cowls (Ref. AMM TASK 71-13-00-010-010):
(a) FOR [1000EM1] (ENGINE-1)
437AL 438AR
(b) FOR [1000EM2] (ENGINE-2)
447AL 448AR.
(2) Put the ACCESS PLATFORM 2M (6 FT) in position.

4. Procedure
Subtask 71-13-00-210-055-A ** ON A/C NOT FOR ALL

A. Examine the fan cowls.

Left Fan Cowl - Outer Skin ** ON A/C NOT FOR ALL

Left Fan Cowl - Inner Skin ** ON A/C NOT FOR ALL

Right Fan Cowl - Outer Skin ** ON A/C NOT FOR ALL

Right Fan Cowl - Inner Skin ** ON A/C NOT FOR ALL

(1) Abrasion, gouge, scratch, nick, delamination, hole, crack and dent.
(a) Refer to NSRM 542000 (RDN 600) for allowable damage data.

5. Close-up
Subtask 71-13-00-410-063-A ** ON A/C NOT FOR ALL

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Close the fan cowls (Ref. AMM TASK 71-13-00-410-010):
(3) FOR [1000EM1] (ENGINE-1)
437AL 438AR
(4) FOR [1000EM2] (ENGINE-2)
447AL 448AR.
(a) Remove the access platform(s).
(b) Remove the WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.01 12:56:10 UTC