[Federal Register Volume 62, Number 74 (Thursday, April 17, 1997)]
[Proposed Rules]
[Pages 18726-18728]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-9880]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-222-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 757 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Boeing Model 757 series 
airplanes. This proposal would require one-time inspections to verify 
proper installation and to detect chafing and/or damage of certain 
rerouted wire bundles; to verify if certain protective grommets are 
installed properly and to detect missing grommets; and various follow-
on actions. This proposal is prompted by a report of smoke and fire in 
the lower left-hand side of the E1-1 rack of the electrical equipment 
bay due to chafing of wire bundles as a result of missing protective 
grommets. The actions specified by the proposed AD are intended to 
prevent chafing of wire bundles, which could result in smoke and fire 
at the E1-1 rack of the electrical equipment bay.

DATES: Comments must be received by May 27, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-222-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays.
    The service information referenced in the proposed rule may be 
obtained from

[[Page 18727]]

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.

FOR FURTHER INFORMATION CONTACT: Forrest Keller, Senior Aerospace 
Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington; 
telephone (206) 227-2790; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed 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 above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with 
the substance of this proposal 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 96-NM-222-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules 
Docket No. 96-NM-222-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received a report indicating that, during power-up of a 
Boeing Model 757 series airplane, smoke and fire were coming from the 
lower left-hand side of the E1-1 rack of the electrical equipment bay. 
Investigation revealed the source of ignition to be electrical arcing 
caused by chafing of wire bundles, having part numbers (P/N) W2608 and 
W4508, at the upper lip of stringer R-23L at approximately station 450. 
These wire bundles had been improperly routed during incorporation of 
Boeing Alert Service Bulletin 757-24A0025, dated May 10, 1985, and 
Boeing Service Bulletin 757-24A0025, Revision 1, dated December 17, 
1987. Further investigation revealed that the protective grommets on 
the upper lip of stringer R-23L were missing on several other Model 757 
series airplanes that also had been modified in accordance with those 
service bulletins. These protective grommets are intended to prevent 
chafing of the wire bundles. These conditions, if not corrected, could 
result in smoke and fire at the E1-1 rack of the electrical equipment 
bay.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
757-24A0025, dated May 10, 1985, and Boeing Service Bulletin 757-
24A0025, Revision 1, dated December 17, 1987, which describe, among 
other things, procedures for replacement of certain grommets with new 
grommets or installation of a new grommet, if a certain grommet is 
improperly installed or missing.
    The FAA has also reviewed and approved Boeing Production 
Installation Drawing 288N4329, Revision H, which describes procedures 
for installation of a protective grommet on the upper edge of 
intercostal R-23L at approximately station 450 between the intercostal 
and wire bundles having P/N's W2608 and W4508.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would require the following:
    1. Performing a one-time inspection to verify proper installation 
and to detect chafing and/or damage of the wire bundles, having P/N's 
W4508, W2608, and W2604, paying particular attention to the area where 
the wire bundles are routed through the web supports and the area over 
the upper edge of intercostal R-23L;
    2. Repairing of chafed or damaged rerouted wire bundles;
    3. Loosening wire bundle clamps, adjusting wire bundles to achieve 
proper clearances, and retightening the wire bundle clamps, if the wire 
bundles are installed improperly;
    4. Performing a one-time inspection to verify if certain protective 
grommets are installed properly and to detect missing grommets, and 
replacing improperly installed grommets with new grommets or installing 
new grommets, as applicable;
    5. Performing a one-time inspection to determine if a protective 
grommet is installed on the upper edge between the intercostal and 
rerouted wire bundles having P/N's W2608 and W4508, at intercostal R-
23L at approximately station 450; and
    6. Installing a protective grommet between the wire bundles and 
intercostal, if no protective grommet is installed.
    Accomplishment of the inspections and re-installation of affected 
wire bundles and protective grommets will prevent chafing of the wire 
bundles, which could result in smoke and fire at the E1-1 rack of the 
electrical equipment bay.
    The replacement and certain grommet installations would be required 
to be accomplished in accordance with the service bulletins described 
previously. Certain other installations would be required to be 
accomplished in accordance with Boeing Production Installation Drawing 
288N4329. The repair would be required to be accomplished in accordance 
with Boeing Standard Wiring Practices Manual 20-10-13.

Cost Impact

    There are approximately 62 Boeing Model 757 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 28 
airplanes of U.S. registry would be affected by this proposed AD, that 
it would take approximately 2 work hours per airplane to accomplish the 
proposed actions, and that the average labor rate is $60 per work hour. 
The cost of required parts would be nominal. Based on these figures, 
the cost impact of the proposed AD on U.S. operators is estimated to be 
$3,360, or $120 per airplane.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the proposed requirements of 
this AD action, and that no operator would accomplish those actions in 
the future if this AD were not adopted.

Regulatory Impact

    The regulations proposed herein would not have substantial direct 
effects on the States, on the relationship between the national 
government and

[[Page 18728]]

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 proposal would not 
have sufficient federalism implications to warrant the preparation of a 
Federalism Assessment.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, will not have a significant economic impact, 
positive or negative, on a substantial number of small entities under 
the criteria of the Regulatory Flexibility Act. A copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
part 39 of the Federal Aviation Regulations (14 CFR part 39) as 
follows:

PART 39--AIRWORTHINESS DIRECTIVES

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

    Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Boeing: Docket 96-NM-222-AD.
    Applicability: Model 757 series airplanes, on which Boeing Alert 
Service Bulletin 757-24A0025, dated May 10, 1985, and/or Boeing 
Service Bulletin 757-24A0025, Revision 1, dated December 17, 1987, 
has been accomplished; excluding variable numbers NA003, NA004, 
NA007, NA009, NA010, NA012 through NA016 inclusive, and NA021; 
certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (b) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent chafing of wire bundles, which could result in smoke 
and fire at the E1-1 rack of the electrical equipment bay, 
accomplish the following:
    (a) Within 6 months after the effective date of this AD, 
accomplish paragraphs (a)(1), (a)(2), and (a)(3) of this AD.
    (1) Perform a one-time inspection to verify proper installation 
and to detect chafing and/or damage of the wire bundles, having part 
numbers (P/N) W4508, W2608, and W2604. Pay particular attention to 
the area where the wire bundles are routed through the web supports 
and the area over the edge of intercostal R-23L.
    (i) If the wire bundles are installed properly and no chafing or 
damage is detected, no further action is required by this paragraph.
    (ii) If any chafing or damage is detected, prior to further 
flight, repair it in accordance with Boeing Standard Wiring 
Practices Manual 20-10-13.
    (iii) If any wire bundle is installed improperly, prior to 
further flight, loosen the wire bundle clamps, adjust the wire 
bundles to achieve proper clearances, and retighten the wire bundle 
clamps.
    (2) Perform a one-time inspection to verify if all protective 
grommets identified in Boeing Alert Service Bulletin 757-24A0025, 
dated May 10, 1985, are installed properly and to detect missing 
grommets. If any grommet is improperly installed or missing, prior 
to further flight, replace the grommet with a new grommet or install 
a new grommet, as applicable, in accordance with the alert service 
bulletin.
    (3) Perform a one-time inspection to determine if a protective 
grommet is installed on the upper edge of intercostal R-23L at 
approximately station 450 between the intercostal and wire bundles 
having P/N's W2608 and W4508. If no protective grommet is installed, 
prior to further flight, install one between the wire bundles and 
intercostal, in accordance with Boeing Production Installation 
Drawing 288N4329, Revision H.
    (b) 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.

    (c) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.

    Issued in Renton, Washington, on April 10, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-9880 Filed 4-16-97; 8:45 am]
BILLING CODE 4910-13-U