[Federal Register Volume 64, Number 193 (Wednesday, October 6, 1999)]
[Proposed Rules]
[Pages 54240-54242]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-26085]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-242-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100, -200, 747SP, and 
747SR Series; Airplanes Equipped With Pratt & Whitney JT9D-7, -7A, -7F, 
and -7J Series Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Boeing Model 747-100, -
200, 747SP, and 747SR series airplanes. This proposal would require 
one-time detailed visual and eddy current inspections to detect 
cracking of the nose cowl mounting flange; rework of the nose cowl 
mounting flange; eddy current inspection to detect cracking of the 
reworked nose cowl mounting flange; and corrective action, if 
necessary. This proposal is prompted by reports of the nose cowl 
separating from the engine and departing the airplane following severe 
engine vibration. The actions specified by the proposed AD are intended 
to prevent separation of the nose cowl from the engine, which could 
cause collateral damage to the airplane, and, possibly, reduced 
controllability of the airplane.

DATES: Comments must be received by November 22, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-242-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 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: Dionne Stanley, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA,

[[Page 54241]]

Transport Airplane Directorate, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2250; fax (425) 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 99-NM-242-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-114, Attention: Rules 
Docket No. 99-NM-242-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that, on certain Boeing 
Model 747 series airplanes equipped with certain Pratt & Whitney JT9D 
series engines, the nose cowl has separated from the engine and 
departed the airplane following severe engine vibration.
    The severe engine vibration was caused by engine damage resulting 
from bird or foreign object ingestion. Separation of the nose cowl from 
the engine, if not corrected, could cause collateral damage to the 
airplane, and, possibly, reduced controllability of the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 747-71-
2290, dated March 18, 1999, which describes procedures for one-time 
detailed visual and eddy current inspections to detect cracking of the 
existing nose cowl mounting flange; rework of the nose cowl mounting 
flange to increase the number of attachment fastener holes from 37 to 
67; and a one-time eddy current inspection to detect cracking of the 
new fastener holes in the reworked nose cowl mounting flange. 
Accomplishment of the actions specified in the service bulletin is 
intended to adequately address the identified unsafe condition.

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 accomplishment of the actions specified in 
the service bulletin described previously, except as discussed below. 
If any cracking is found during any inspection, corrective actions 
would be required to be accomplished in accordance with a method 
approved by the FAA.

Differences Between Proposed Rule and Service Bulletin

    Operators should note that the service bulletin does not recommend 
any compliance time for accomplishing the nose cowl inspections and 
rework. In developing an appropriate compliance time for this AD, the 
FAA considered the degree of urgency associated with addressing the 
subject unsafe condition, the average utilization of the affected 
fleet, and the time necessary to perform the inspections and rework. In 
light of all of these factors, the FAA finds a 24-month compliance time 
for initiating the required actions to be warranted, in that it 
represents an appropriate interval of time allowable for affected 
airplanes to continue to operate without compromising safety.

Cost Impact

    There are approximately 257 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 106 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
19 work hours per airplane to accomplish the proposed actions, and that 
the average labor rate is $60 per work hour. Required parts would cost 
approximately $500 per airplane. Based on these figures, the cost 
impact of the proposed AD on U.S. operators is estimated to be 
$173,840, or $1,640 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 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.

[[Page 54242]]

Sec. 39.13  [Amended]

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

Boeing: Docket 99-NM-242-AD.

    Applicability: Model 747-100, -200, 747SP, and 747SR series 
airplanes; certificated in any category; equipped with Pratt & 
Whitney JT9D-7, -7A, -7F and -7J series engines.

    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 (d) 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 separation of the nose cowl from the engine, which 
could cause collateral damage to the airplane, and, possibly, 
reduced controllability of the airplane, accomplish the following:

One-Time Inspections and Rework

    (a) Within 24 months after the effective date of this AD, 
perform one-time detailed visual and eddy current inspections to 
detect cracking of the existing nose cowl mounting flange, rework 
the nose cowl mounting flange to increase the number of attachment 
fastener holes from 37 to 67, and perform a one-time eddy current 
inspection to detect cracking of the new fastener holes in the 
reworked nose cowl mounting flange, in accordance with the 
Accomplishment Instructions of Boeing Service Bulletin 747-71-2290, 
dated March 18, 1999.
    Note 2: For the purposes of this AD, a detailed visual 
inspection is defined as ``An intensive visual examination of a 
specific structural area, system, installation, or assembly to 
detect damage, failure, or irregularity. Available lighting is 
normally supplemented with a direct source of good lighting at 
intensity deemed appropriate by the inspector. Inspection aids such 
as mirror, magnifying lenses, etc., may be used. Surface cleaning 
and elaborate access procedures may be required.''

Corrective Action

    (b) If any crack is found during any inspection required by 
paragraph (a) of this AD: Prior to further flight, repair in 
accordance with a method approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA, Transport Airplane Directorate.
    (c) As of the effective date of this AD, no person shall install 
a nose cowl on any airplane, unless it has been inspected and 
modified in accordance with paragraph (a) of this AD.

Alternative Methods of Compliance

    (d) 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 ACO. 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 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permits

    (e) Special flight permits may be issued in accordance with 
Secs. 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 September 30, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-26085 Filed 10-5-99; 8:45 am]
BILLING CODE 4910-13-U