1. Planning Information

A. Effectivity

Boeing 747 and Boeing 767

All RB211-524 Engines with Lightweight Thrust Reverser.

RB211-524D4-19, 524D4-B-19, 524D4-39, 524D4-B-39, 524D4X-19, 524D4X-B-19

Propulsion Systems.

RB211-524G, 524G-T, 524H, 524H-T Engines.

RB211-TR525-19-A, TR525-19-B, TR526-39-A, TR526-39-B, TR528-19-A, TR528-19-B,

TR529-19-A, TR529-19-B, TR530-19-A, TR530-19-B, TR532-39-A, TR532-39-B,

TR533-39-A, TR533-39-B, TR534-39-A, TR534-39-B, TR537-19-A, TR537-19-B,

TR537-36-A, TR537-36-B, TR538-19-A, TR538-19-B, TR538-36-A, TR538-36-B,

TR541-19-A, TR541-19-B, TR541-36-A, TR541-36-B, TR542-19-A, TR542-19-B,

TR542-36-A, TR542-36-B, TR556-19-A, TR556-19-B, TR557-19-A, TR557-19-B,

TR558-19-A, TR558-19-B, TR559-19-A, TR559-19-B, TR560-39-A, TR560-39-B,

TR561-39-A, TR561-39-B, TR562-39-A, TR562-39-B, TR563-39-A, TR563-39-B Thrust

Reversers.

B. Reason

A detailed investigation into the loss of a Thrust Reverser Unit (TRU) during

landing has identified the reason to be a progressive detachment of TRUs fixed

structure front ring rivet lines on the rear flange. This then lead to the

subsequent fracture of the rivets around its forward flange. Rolls-Royce has

concluded that the loss of the rivet lines was directly linked to a previous

translating cowl gearbox stubshaft fracture and the subsequent repair of the

fixed structure to Engine Manual repair FRS5887 (see References (1.H.)).

FRS5887 instructs the replacement of the damaged section of structure, but

recent stress and impact analysis utilising the latest technology and

techniques indicates that rivets adjacent to the repair, and currently not

replaced, are likely to have been overloaded above their elastic limit. Rivets

on the structures rear ring may also have been overloaded even if there was no

visible damage.

It is therefore necessary to instruct the replacement of these potentially

yielded rivets from units in service in order to prevent a further Thrust

Reverser loss.

RB211-524 LIGHTWEIGHT THRUST REVERSER - REPLACEMENT OF DAMAGED RIVETS ON THRUST

REVERSER FIXED STRUCTURE - NON-MODIFICATION SERVICE BULLETIN - NON - MOD.78-AG084

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Furthermore, if the gearbox stubshaft fracture event was relatively severe,

indicated by the structures rear ring also requiring repair to either FRS4976

or FRS6669 (see References (1.H.)), the level of overload to the structures

front ring rivets is increased. A shorter reaction time is therefore required

to rectify the situation when rear ring structural repairs have been embodied

at the same time as FRS5887 (see References (1.H.)).

Non-Modification Service Bulletin (NMSB) 78-AF573 (see References (1.H.)) was

issued in September 2007 which identified thrust reverser units that had

previously been repaired to FRS5887 (see References (1.H.)) and hence would

have experienced a thrust reverser stubshaft fracture. The results of this

survey should be used to identify which engines are subject to this Alert NMSB.

Revision 1 of this NMSB was issued to include an engine mark that was

unintentionally omitted.

Revision 2 of this NMSB is issued to extend the time frames for Compliance.

C. Compliance

ALERT

Compliance is in accordance with the criteria in Table 1 and in zones as

identified in Fig.1.

This NMSB is anticipated to be subject to the incorporation requirements of an

EASA Airworthiness Directive.

D. Approval

The technical content of this Non-Modification Service Bulletin was approved

under the authority of Design Organisation Approval EASA.21J.035 on Nov.28/08

and re-approved on Xxx.XX/09.

E. Manpower

The Non-Modification Service Bulletin can only be accomplished in shop

(1) Time to gain access

Not applicable

(2) Time to embody

40 hours

(3) Time to restore to serviceable condition

Not applicable

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F. Material Price and Availability

Not applicable

G. Tooling Price and Availability

Required tooling is listed in relevant removal/installation procedure, provided

in References (1.H.).

H. References

(1) RB211-524 Reference Service Bulletins

78-AF573

Lightweight Thrust Reverser - Inspection for evidence of loose or missing

rivets on thrust reverser attachment flange - Non-Modification Service

Bulletin

(2) Engine Manual, 78-32-00, Removal and Installation

(3) Engine Manual, 78-32-00, Disassembly and Assembly

(4) Engine Manual, 78-32-06-300-023, Thrust Reverser Fixed Structure - Rear

Ring Assembly - Replace Damaged Rear Ring (FRS4976) - REPAIR 023

(5) Engine Manual, Task 78-32-06-300-033, Thrust reverser - Fixed structure,

front ring - Repair damaged outer web at the number two and/or three

gearbox positions by fitting replacement section, FRS5887 - REPAIR 033

(6) Engine Manual, Task 78-32-06-300-040, T/R fixed structure rear ring -

repair damaged front flange by replacement of section, FRS6669 - REPAIR

118

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2. Material Information

None.

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3. Accomplishment instructions

A. Procedure

(1) Remove the thrust reverser unit in accordance with the following Engine

Manual tasks:

RB211-524D4, Engine Manual - 2RR, TASK 78-32-00-000-001-B01, Remove Thrust

Reverser (Lightweight), CONFIG-2

RB211-524G/H-T, Engine Manual - 7RR, TASK 78-32-00-000-001, Remove Thrust

Reverser - REMOVAL

(2) Disassemble the thrust reverser unit in accordance with the following

relevant Engine Manual tasks to a suitable level to allow access to rework

the fixed structure front and rear ring assemblies (EIPC ref. 78-32-06,

Fig/Item No. 05-570 and 05-025):

RB211-524D4, Engine Manual - 2RR, TASK 78-32-00-000-000-B01, Disassemble

Cold Stream Thrust Reverser System - DISASSEMBLY, CONFIG-2

RB211-524G/H-T, Engine Manual - 7RR, TASK 78-32-00-000-000-B01,

Disassemble Cold Stream Thrust Reverser System - DISASSEMBLY

(3) Incorporate FRS5887 Part 2 and 4.B. on the fixed structures front ring,

following the instructions in the repair scheme.

(4) Incorporate FRS6669 Part 2 on the fixed structures rear ring, following

the instructions in the repair scheme. If FRS4976 was accomplished at the

time or subsequently to the TRU gearbox stubshaft fracture then

Accomplishment Instructions 3.A.(4) can be omitted.

(5) Record incorporation of Non-Modification Service Bulletin on the thrust

reversers data plate.

(6) Assemble the thrust reverser unit in accordance with the following Engine

Manual tasks:

RB211-524D4, Engine Manual - 2RR, TASK 78-32-00-400-000, Assemble Cold

Stream Thrust Reverser System - ASSEMBLY, CONFIG-2

RB211-524G/H-T, Engine Manual - 7RR, TASK 78-32-00-400-001, Assemble Cold

Stream Thrust Reverser System - ASSEMBLY

(7) Fit the thrust reverser unit to engine in accordance with the following

Engine Manual tasks:

RB211-524D4, Engine Manual - 2RR, TASK 78-32-00-400-000-B01, Install

Thrust Reverser (Lightweight) - INSTALLATION, CONFIG-2

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RB211-524G/H-T, Engine Manual - 7RR, TASK 78-32-00-400-000, Install Thrust

Reverser - INSTALLATION

B. A record of accomplishment is required.

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Thrust Reverser Unit

Fig.1

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NMSB 78-AG084 Table of Compliance

Table 1

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