Airworthiness Directives; Boeing Model 757 Series Airplanes Equipped With Rolls Royce Engines

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-NM-02-AD; Amendment 39-8822; AD 94-04-04]

Airworthiness Directives; Boeing Model 757 Series Airplanes

Equipped With Rolls Royce Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that

is applicable to certain Boeing Model 757 series airplanes. This action

requires inspections to detect fatigue-related cracking or breakage of

the hydraulic tubing support brackets located on the upper spar web in

the engine struts; further inspection to detect related damage of the

upper spar web, the fuel lines, and the hydraulic lines, as necessary;

and repair or replacement of cracked or damaged parts. This action also

provides for an optional terminating action which, if accomplished,

would eliminate the need for the required inspections. This amendment

is prompted by reports of fatigue-related cracks in the hydraulic

tubing support brackets located on the upper spar web in the engine

struts. The actions specified in this AD are intended to prevent fire

or explosion in the interior of the engine struts.

DATES: Effective February 28, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of February 28, 1994.

Comments for inclusion in the Rules Docket must be received on or

before April 12, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-103,

Attention: Rules Docket No. 94-NM-02-AD, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056.

The service information referenced in this AD may be obtained from

Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington

98124-2207. This information may be examined at the FAA, Transport

Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at

the Office of the Federal Register, 800 North Capitol Street, NW.,

suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Sheila Mariano, Aerospace Engineer,

Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane

Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue,

SW., Renton, Washington 98055-4056; telephone (206) 227-2675; fax (206)

227-1182.

SUPPLEMENTARY INFORMATION: The FAA has recently received reports from

Boeing that operators have reported fatigue-related cracks in the

hydraulic tubing support brackets located on the upper spar web of the

engine struts in several Model 757 series airplanes. The cracked

support brackets were manufactured from 2219 aluminum alloy. On one

airplane, a support bracket cracked completely and the clamp assembly

wore a hole in the upper spar web. (A bracket that is completely

cracked can permit the clamp assembly to loosen and rotate on the

hydraulic line.) On another airplane, a support bracket cracked

completely and the clamp assembly wore a hole in the fuel feed line

located next to the hydraulic pressure line.

The interior part of the strut contains ignition sources. The upper

spar web acts as a seal to keep fluids and vapors from hydraulic lines

and fuel lines out of the interior part of the strut, where the

pneumatic bleed air ducts are located. If fluids leak from the fuel

line or the hydraulic lines that are on top of the upper spar web,

those fluids will drain from the strut through the strut drain system.

If the upper spar web has a hole in it and fuel or hydraulic fluid

leaks occur, then those fluids could drain into the interior of the

strut. The surface temperatures of the bleed air ducts are hot enough

to be an ignition source. Fatigue-related cracking in the hydraulic

tubing support brackets, if not detected and corrected in a timely

manner, could result in fuel or hydraulic fluid leaking and draining

into the interior of the strut, which could result in fire or

explosion.

The FAA has reviewed and approved Boeing Alert Service Bulletin

757-54A-0030, Revision 1, dated December 20, 1993, that describes

procedures for performing a one-time inspection on Group Two airplanes

using a magnet to determine whether the forward support bracket for the

hydraulic tubing in the upper spar web of each strut is manufactured

from 17-7PH steel. (No further inspection is recommended for support

brackets manufactured from 17-7PH steel, since it is not subject to the

identified fatigue cracking problems.) For Group Two airplanes, the

forward bracket is manufactured from either 17-7PH steel or 2219

aluminum alloy; the remainder of the support brackets (two to four

brackets) are manufactured from 17-7PH steel. Group One airplanes are

not equipped with 17-PH steel brackets. The alert service bulletin also

describes procedures for performing an initial visual inspection to

detect fatigue-related cracking or breakage of all non-17-7PH steel

support brackets. If any completely broken or cracked support bracket

is found as a result of the initial inspection, this alert service

bulletin describes procedures for performing a further visual

inspection to detect related damage of the upper spar web, the fuel

lines, and the hydraulic lines, as necessary; repair or replacement of

damaged parts with new or serviceable parts; and removal of any broken

or cracked support brackets. This alert service bulletin also describes

procedures for replacing the existing support brackets with new nickel

alloy support brackets. Finally, this alert service bulletin recommends

that a limited number of flights be permitted prior to replacement of

any removed support bracket with a new nickel alloy support bracket.-

Since an unsafe condition has been identified that is likely to

exist or develop on other Boeing Model 757 series airplanes of the same

type design, this AD is being issued to prevent fire or explosion in

the interior of the engine struts. This AD requires the following

actions: -

1. A one-time inspection using a magnet to determine whether the

forward support bracket for the hydraulic tubing in the upper spar web

of each engine strut is manufactured from 17-7PH steel. No further

action is necessary for support brackets manufactured from 17-7PH

steel. -

2. An initial visual inspection to detect fatigue-related cracking

or breakage of all support brackets that are not manufactured from 17-

7PH steel. -

3. If any completely broken or cracked support bracket is found as

a result of the initial inspection, a further visual inspection to

detect related damage of the upper spar web, the fuel lines, and the

hydraulic lines, as necessary.

4. Repair or replacement of damaged parts with new or serviceable

parts.

5. Removal and replacement of any broken or cracked support

brackets.

The actions are required to be accomplished in accordance with the

alert service bulletin described previously.

This AD also requires repetitive inspections for airplanes having

one or more support brackets that are manufactured from 2219 aluminum,

2024-T42 aluminum alloy, or 301 stainless steel. The repetitive

inspections would be required to be performed in accordance with the

procedures described in the alert service bulletin.

This AD also provides for replacement of the existing support

brackets on the upper spar web of each engine strut with new nickel

alloy support brackets. If accomplished at all locations, this

replacement would terminate the need for all of the required

inspections. If accomplished, this replacement is required to be

performed in accordance with the alert service bulletin described

previously.

This AD specifies that if certain brackets are found cracked or

broken, a certain number of further flights are allowed prior to

replacement of the bracket, provided that:

(1) Cracked or broken brackets are removed completely;

(2) Damaged spar webs are repaired, and

(3) Damaged fuel lines and hydraulic lines are repaired or

replaced.

This is considered to be interim action. The FAA is currently

considering requiring the replacement of all existing support brackets

manufactured from 2219 aluminum, 2024-T42 aluminum alloy, or 301

stainless steel with new nickel alloy support brackets, which will

constitute terminating action for the inspections required by this AD

action. However, the proposed compliance time for the installation of

the modification is sufficiently long so that notice and public comment

would not be impracticable. -

Since a situation exists that requires the immediate adoption of

this regulation, it is found that notice and opportunity for prior

public comment hereon are impracticable, and that good cause exists for

making this amendment effective in less than 30 days.

Comments Invited

Although this action is in the form of a final rule that involves

requirements affecting flight safety and, thus, was not preceded by

notice and an opportunity for public comment, comments are invited on

this rule. Interested persons are invited to comment on this rule by

submitting such written data, views, or arguments as they may desire.

Communications shall identify the Rules Docket number and be submitted

in triplicate to the address specified under the caption ADDRESSES. All

communications received on or before the closing date for comments will

be considered, and this rule may be amended in light of the comments

received. Factual information that supports the commenter's ideas and

suggestions is extremely helpful in evaluating the effectiveness of the

AD action and determining whether additional rulemaking action would be

needed. -

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the rule that might

suggest a need to modify the rule. All comments submitted will be

available, both before and after the closing date for comments, in the

Rules Docket for examination by interested persons. A report that

summarizes each FAA-public contact concerned with the substance of this

AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments

submitted in response to this notice must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket Number 94-NM-02-AD.'' The postcard will be date stamped and

returned to the commenter.

The regulations adopted herein will not have substantial direct

effects on the States, on the relationship between the national

government and the States, or on the distribution of power and

responsibilities among the various levels of government. Therefore, in

accordance with Executive Order 12612, it is determined that this final

rule does not have sufficient federalism implications to warrant the

preparation of a Federalism Assessment. -

The FAA has determined that this regulation is an emergency

regulation that must be issued immediately to correct an unsafe

condition in aircraft, and is not a ``significant regulatory action''

under Executive Order 12866. It has been determined further that this

action involves an emergency regulation under DOT Regulatory Policies

and Procedures (44 FR 11034, February 26, 1979). If it is determined

that this emergency regulation otherwise would be significant under DOT

Regulatory Policies and Procedures, a final regulatory evaluation will

be prepared and placed in the Rules Docket. A copy of it, if filed, may

be obtained from the Rules Docket at the location provided under the

caption ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by

reference, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration amends 14 CFR part

39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES -

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

Sec. 39.13 [Amended] -

2. Section 39.13 is amended by adding the following new

airworthiness directive:

94-04-04 Boeing: Amendment 39-8822. Docket 94-NM-02-AD.

-Applicability: Model 757 series airplanes equipped with Rolls

Royce engines; as listed in Boeing Alert Service Bulletin 747-

54A0030, Revision 1, dated December 20, 1993; certificated in any

category. -

Compliance: Required as indicated, unless accomplished

previously. -

To prevent fire or explosion in the interior of the engine

struts, accomplish the following:

(a) For Group 2 Airplanes: Within 60 days after the effective

date of this AD, perform an inspection using a magnet to determine

whether the forward support bracket for the hydraulic tubing on the

upper spar web of each engine strut is manufactured from 17-7PH

steel, in accordance with Boeing Alert Service Bulletin 757-54A0030,

Revision 1, dated December 20, 1993. If any forward support bracket

is manufactured from 17-7PH steel, no further action is required by

this AD for that forward bracket.

Note 1: The brackets positioned after the forward bracket should

be manufactured from 17-7PH steel, as shown below:

------------------------------------------------------------------------

(Power plant

Bracket-part number- station

number)

------------------------------------------------------------------------

-First Bracket-312N5817-13 (or equivalent)-.............. PPS 102

Second Bracket-312N5817-19 (or equivalent)-.............. PPS 120

Third Bracket-312N5817-23 (or equivalent)-............... PPS 129

Fourth Bracket-312N5817-25 (or equivalent)-.............. PPS 145

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(b) For Groups 1 and 2 Airplanes: Within 60 days after the

effective date of this AD (for Group 1 airplanes), and prior to further

flight following the inspection required by paragraph (a) of this AD

(for Group 2 airplanes), perform an initial visual inspection to detect

fatigue-related cracks or breakage on the hydraulic tubing support

brackets not manufactured of 17-7PH steel on the upper spar web of each

engine strut, in accordance with Boeing Alert Service Bulletin 757-

54A0030 , Revision 1, dated December 20, 1993. If any discrepancy is

detected, prior to further flight, accomplish the following in

accordance with the alert service bulletin:

(1) For any support bracket that is completely broken: Perform a

further visual inspection to detect worn areas or other damage of the

upper spar web, the fuel lines, and the hydraulic lines; and prior to

further flight, accomplish paragraphs (b)(1)(i), (b)(1)(ii),

(b)(1)(iii) and (b)(1)(iv) of this AD in accordance with the alert

service bulletin:

(i) Repair any damaged upper spar web.

(ii) Repair or replace any damaged fuel line with new or

serviceable parts, as necessary.

(iii) Replace any damaged hydraulic line with new or serviceable

parts.

(iv) Remove any broken support bracket; and, except as provided by

paragraph (c) of this AD, replace it with a new nickel alloy bracket.

(2) For any support bracket that is cracked, but not completely

broken: Perform a further visual inspection to detect damage of the

hydraulic pressure line only; and prior to further flight, accomplish

paragraphs (b)(2)(i) and (b)(2)(ii) of this AD in accordance with the

alert service bulletin:

(i) Replace any damaged hydraulic pressure line with new or

serviceable parts, as necessary.

(ii) Remove any cracked support bracket; and, except as provided by

paragraph (c) of this AD, replace it with a new nickel alloy bracket.

(c) For any airplane having a support bracket that is removed

during accomplishment of paragraph (b)(1)(iv) or (b)(2)(ii) of this AD:

The following number of flights are permitted prior to replacement of

any removed support bracket with a new nickel alloy bracket (in

accordance with Boeing Alert Service Bulletin 757-54A0030, Revision 1,

dated December 20, 1993), provided that, prior to further flight, the

cracked or broken brackets are removed completely, damaged spar webs

are repaired, and fuel lines and hydraulic lines are repaired or

replaced, in accordance with paragraph (b) of this AD:

------------------------------------------------------------------------

Bracket-part number-(power plant

station number) Flights permitted

------------------------------------------------------------------------

First Bracket Removed P/N 312N5817- No Flights.

55 (PPS 102)-.

Second Bracket Removed P/N 312N5817- Ten Flights.

69 (PPS 120)-.

Third Bracket Removed P/N 312N5817- Ten Flights.

73 (PPS 129)-.

Fourth Bracket Removed P/N 312N5817- Three Flights.

75 (PPS 145)-.

Second and Third Brackets Removed-. One Flight.

Multiple Brackets, other than No Flights.

Second and Third-.

------------------------------------------------------------------------

(d) For any airplane having a support bracket that is manufactured

from 2024-T42 aluminum alloy or 301 stainless steel: Repeat the initial

inspection required by paragraph (b) of this AD thereafter at intervals

not to exceed 2,000 flight hours in accordance with the procedures

described in Boeing Alert Service Bulletin 757-54A0030, Revision 1,

dated December 20, 1993.

(e) For any airplane having a support bracket that is manufactured

from 2219 aluminum: Repeat the initial inspection required by paragraph

(b) of this AD thereafter at intervals not to exceed 1,000 flight hours

in accordance with the procedures described in Boeing Alert Service

Bulletin 757-54A0030, Revision 1, dated December 20, 1993.

(f) Installation of new nickel alloy hydraulic tubing support

brackets for the hydraulic tubing on the upper spar web of the engine

struts at all locations in accordance with the requirements of Boeing

Alert Service Bulletin 757-54A0030, Revision 1, dated December 20,

1993, constitutes terminating action for the requirements of this AD.

(g) As of the effective date of this AD, no person shall install

any hydraulic tubing support bracket on the upper spar web of the

engine struts that is manufactured from 2219 aluminum, 2024-T42

aluminum alloy, or 301 stainless steel on any airplane.

(h) An alternative method of compliance or adjustment of the

compliance time that provides an acceptable level of safety may be used

if approved by the Manager, Seattle Aircraft Certification Office

(ACO), FAA, Transport Airplane Directorate. Operators shall submit

their requests through an appropriate FAA Principal Maintenance

Inspector, who may add comments and then send it to the Manager,

Seattle ACO.

Note 2: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be obtained

from the Seattle ACO.

(i) Special flight permits may be issued in accordance with FAR 2nd

21.199 to operate the airplane to a location where the requirements of

this AD can be accomplished.

(j) The inspections, repairs and replacement shall be done in

accordance with Boeing Alert Service Bulletin 757-54A0030, Revision 1,

dated December 20, 1993. This incorporation by reference was approved

by the Director of the Federal Register in accordance with 5 U.S.C.

552(a) and 1 CFR part 51. Copies may be obtained from Boeing Commercial

Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies

may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind

Avenue, SW., Renton, Washington; or at the Office of the Federal

Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(k) This amendment becomes effective on February 28, 1994.

Issued in Renton, Washington, on February 4, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-3105 Filed 2-10-94; 8:45 am]

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