Visually Examine the Air Intake Cowl - Allowable Damage Data [IAE]

TASK 71-11-11-200-011-A
Visually Examine the Air Intake Cowl - Allowable Damage Data

ZONE: 400

1. Reason for the Job
This task gives the procedure for the inspection of the air intake cowl to determine allowable damage.
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
400	POWER PLANT, NACELLES AND PYLONS
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 541000
Air Intake Cowl Lip Skin
Air Intake Cowl Outer Barrel
Air Intake Cowl Titanium Aft Bulkhead, A5 (serial no. N7354 and sub)
Air Intake Cowl 3 Acoustic Inner Barrel
Air Intake Cowl 2 Acoustic Inner Barrel
Air Intake Exhaust Panel Grille
Air Intake Cowl Aerodynamic Sealant zones

3. Job Set-up
Subtask 71-11-11-869-050-A ** ON A/C NOT FOR ALL

A. 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.
(1) Material Types
The materials used in the construction of the inlet cowl are aluminium alloys, corrosion resistant steels (CRES), titanium and graphite fabric of various weaves and forms. These forms include honeycomb (NOMEX), closed-weave fabric, open-weave fabric, and tape. CRES is used for tubes, ducts, fittings and accessories. The main aluminium alloy component in the inlet cowl is the one-piece pressed inlet lip skin. On A1 and A5 (serial no. V001 to V999 and N0001 to N7353) aluminium alloy honeycomb is used in the core of the composite sandwich which makes up the aft bulkhead. On A5 (serial no. N7354 and sub) the rear bulkheadis made of three titanium web segments.
(2) 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 no later than the next 6000 flight hours, 4500 flight cycles or 20 months. The location and size of the damage is to be noted and checked at each subsequent 600 flight hours, 750 flight cycles or 100 days check to make sure that the damage has not grown beyond the time limited damage allowances. If the damage is more than the allowable size, it must be repaired before the next flight.

(3) Damage Types
The types of allowable damage permitted on the inlet 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 has 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. There is no change in the cross sectional area. Area boundaries are smooth. Its form is usually the result of contact with a smoothly contoured object.
rip/tear (woven wires) - A rip or a tear in the woven wire of an acoustic bonded panel is a sharp continuous separation of the wire fibers.
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.
void - Separation of the face sheet from the honeycomb core or faying surface.

(4) Zones
(a) The allowable damages zones for the inlet cowl are:

zone G: Capping strap - A1 hybrid (serial no. V299 to V999) and A5 only.
zone K1: Lip skin, inner intake surface (between 135 and 225 degrees)
zone H: Lip skin, inner intake surface (all other areas)
zone K2: Lip skin, outer intake surface (between 315 and 45 degrees)
zone J: Lip skin, outer intake surface (all other areas)
zone R: Panel frame, power plant radial - (PPR230)
zone S: Panel frame - (PPR240)
zone T: Access panel frame - (PPR340)
zone U: Circumferential stiffeners, power plant station - (PPS 35.32) (TOP)
zone V: Splice lands - barrel panels - (PPR 237 and PPR 57)
zone W: Panels lands, front and rear
zone X: Outer barrel panel - (PPR 123 - 180 - 223)
zone Y: Outer barrel panel - (PPR 237 - 0 - 123)
zone Z: Composite aft bulkhead. A1 and A5 (serial N° V001 to V999 and N0001 to N7353)

(b) The allowable damages zones for the titanium bulkhead are:

zone Z: Titanium aft bulkhead. A5 (serial N° N7354 and sub)
zone ZA: Titanium aft bulkhead web (PPR330 - PPR0 - PPR30).
zone ZB: Titanium aft bulkhead web (PPR30 - PPR111 and PPR249 - PPR330).
zone ZC: Titanium aft bulkhead web (PPR111 - PPR180 - PPR249).
zone Z1: Titanium aft bulkhead aluminium alloy zed stiffeners.
zone Z2: Titanium aft bulkhead titanium web joint channels (PPR43, 198 and 317).

NOTE: Flaked, cracked or missing paint in zones ZA, ZB, ZC and Z2 is acceptable. Any loose paint should be removed.

zone N1, P1 and Q1: Woven wire air-wetted surface overlay.
zone N2, P2 and Q2: Woven fibre inner face sheet.
zone N3, P3 and Q3: Honeycomb core.
Zone K, L and M: Splice joints.

(d) The allowable damages zones for the inlet cowl 2 panel acoustic inner barrel are:

zone N1 and P1: Woven wire air-wetted surface overlay.
zone N2 and P2: Woven fibre inner face sheet.
zone N3 and P3: Honeycomb core.
zone K and L: Splice joints.

(e) The allowable damages zones for the inlet cowl anti-ice exhaust panel grille are:

zone C: Grille.

(f) The allowable damages zones for the inlet cowl aerodynamic sealant are:

zone E: Aerodynamic sealant, outer intake joint.
zone F: Aerodynamic sealant, inner intake joint.

Subtask 71-11-11-941-055-A ** ON A/C NOT FOR ALL

B. 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 71-11-11-010-055-A ** ON A/C NOT FOR ALL

C. 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 71-11-11-210-053-A ** ON A/C NOT FOR ALL

A. Examine the Air Intake Cowl Lip Skin

Air Intake Cowl Lip Skin ** ON A/C NOT FOR ALL

(1) Abrasion, dent, gouge, scratch, nick, crack, hole and fastener loss:
(a) Refer to NSRM 541000 (RDN 600) Allowable Damage.

Subtask 71-11-11-210-054-A ** ON A/C NOT FOR ALL

B. Examine the Air Intake Cowl Outer Barrel

Air Intake Cowl Outer Barrel ** ON A/C NOT FOR ALL

(1) Abrasion, gouge, scratch, nick, delamination, crack and hole:
(a) Refer to NSRM 541000 (RDN 600) Allowable Damage.

Subtask 71-11-11-210-075-A ** ON A/C NOT FOR ALL

C. Examine Titanium Aft Bulkhead Structure. A5 (serial no. N7354 and sub).

Air Intake Cowl Titanium Aft Bulkhead, A5 (serial no. N7354 and sub) ** ON A/C NOT FOR ALL

(1) Abrasion, gouge, scratch, nick, dent, crack and hole:
(a) Refer to NSRM 541000 (RDN 600) Allowable Damage.

Subtask 71-11-11-210-055-A ** ON A/C NOT FOR ALL

D. Examine the Air Intake Cowl Acoustic Inner Barrel (3-piece)

PRE SBN 70-0909

Air Intake Cowl 3 Acoustic Inner Barrel ** ON A/C NOT FOR ALL

(1) Scratch, gouge, nick, dent, rip/tear, delamination, void and hole:
(a) Refer to NSRM 541000 (RDN 600) Allowable Damage.

END OF PRE SBN 70-0909

Subtask 71-11-11-210-071-A ** ON A/C NOT FOR ALL

E. Examine the Air Intake Cowl Acoustic Inner Barrel (2-piece)

POST SBN 70-0909

Air Intake Cowl 2 Acoustic Inner Barrel ** ON A/C NOT FOR ALL

(1) Scratch, gouge, nick, dent, rip/tear, delamination, void and hole:
(a) Refer to NSRM 541000 (RDN 600) Allowable Damage.

END OF POST SBN 70-0909

Subtask 71-11-11-210-076-A ** ON A/C NOT FOR ALL

F. Examine the Air Intake Cowl Anti-Ice Exhaust Panel Grille

Air Intake Exhaust Panel Grille ** ON A/C NOT FOR ALL

(1) Crack
(a) Refer to NSRM 541000 (RDN 600) Allowable Damage.

Subtask 71-11-11-210-077-A ** ON A/C NOT FOR ALL

G. Examine Air Intake Cowl Aerodynamic Sealant Zones

Air Intake Cowl Aerodynamic Sealant zones ** ON A/C NOT FOR ALL

(1) Loose or missing sealant at zones E, F and G:
(a) Refer to NSRM 541000 (RDN 600) Allowable Damage.

5. Close-up
Subtask 71-11-11-410-053-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):
(a) FOR [1000EM1] (ENGINE-1)
437AL 438AR.
(b) FOR [1000EM2] (ENGINE-2)
447AL 448AR.
(3) Remove the access platform(s).
(4) Remove the WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.01 02:28:53 UTC