[Federal Register Volume 65, Number 116 (Thursday, June 15, 2000)]
[Proposed Rules]
[Pages 37497-37500]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-15190]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-377-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes

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 series 
airplanes. This proposal would require inspections to detect cracking 
of the frame web, doubler, and inner chord of the forward edge frame of 
main entry door number 1, and various follow-on actions. This proposal 
is prompted by reports of cracking in the frame web, doubler, inner 
chord, and strap of the forward edge frame of main entry door number 1. 
The actions specified by the proposed AD are intended to prevent cracks 
in the frame web and doubler of the forward edge frame of main entry 
door number 1, which could result in inability of the edge frame to 
react door stop loads, and consequent rapid depressurization of the 
airplane.

DATES: Comments must be received by July 31, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-377-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: Rick Kawaguchi, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-1153; 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-377-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-377-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that cracking has been 
detected in the frame web, doubler,

[[Page 37498]]

inner chord, and strap of the forward edge frame of main entry door 
number 1 on several Boeing Model 747 series airplanes. One operator 
reported that the frame web, doubler, inner chord, and strap were 
severed at the lower sill. Cracks initiated in the frame web at the 
fastener holes where the sill attach clip attaches to the frame web. 
Other operators have reported small cracks in the frame web and doubler 
at the cable penetration just below the lower sill. On certain Boeing 
Model 747 series airplanes, the subject frame web, doubler, and inner 
chord are made from 7075 aluminum. Fatigue cracks in the frame web and 
doubler of the forward edge frame of main entry door number 1, if not 
detected, could extend to the inner chord of the frame and cause the 
inner chord to break, leading to failure of the outer chord and 
adjacent fuselage skin. This condition, if not corrected, could result 
in inability of the edge frame to react door stop loads, and consequent 
rapid depressurization of the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 747-
53A2417, Revision 1, dated July 23, 1998, which describes procedures 
for detailed visual and high frequency eddy current (HFEC) inspections 
to detect cracking of the frame web, doubler, and inner chord of the 
forward edge frame of main entry door number 1, and various follow-on 
actions. If no cracking is detected, follow-on actions include 
repetitive detailed visual and HFEC inspections, reinforcement of the 
forward edge frame and repetitive detailed visual inspections, and 
eventual repair of the door frame. If any cracking is detected, the 
repair is required prior to further flight. The repair includes 
replacement of the existing frame web and doubler with a new frame web, 
doubler, and splice doubler made of 2024-T3 aluminum, which is a more 
fatigue-resistant material than 7075 aluminum. Accomplishment of the 
repair eliminates the need for the repetitive inspections described by 
the service bulletin.

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.

Difference Between This Proposed AD and Service Information

    As described previously, the service bulletin describes procedures 
for detailed visual and HFEC inspections to detect cracking of the 
frame web, doubler, and inner chord of the forward edge frame of main 
entry door number 1. Operators should note that paragraph (c) of this 
proposed AD also would require certain repetitive detailed visual 
inspections not described in the service bulletin. These additional 
inspections are prompted by two reports that cracking was detected 
outside the area covered by the service bulletin. As a result of the 
reports, the FAA has determined that it is necessary to propose 
additional repetitive inspections. These additional inspections involve 
removal of the cover assembly for the body torque tube located between 
the door hinge attachments, and accomplishment of a detailed visual 
inspection to detect cracking of the aft side of the forward edge door 
frame web of main entry door number 1. The area to be inspected 
includes the exposed area from doorstop 2 [approximately water 
line (WL) 218] to doorstop 5 (approximately WL 245) at body 
station 434.

Cost Impact

    There are approximately 685 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 211 airplanes of U.S. registry 
would be affected by this proposed AD.
    For Group 1 airplanes (approximately 191 U.S.-registered 
airplanes), it would take approximately 3 work hours per airplane to 
accomplish the proposed inspections, at an average labor rate of $60 
per work hour. Based on these figures, the cost impact of the proposed 
inspections on U.S. operators of Group 1 airplanes is estimated to be 
$34,380, or $180 per airplane, per inspection cycle.
    For Group 2 airplanes (approximately 20 U.S.-registered airplanes), 
it would take approximately 2 work hours per airplane to accomplish the 
proposed inspections, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of the proposed inspection on 
U.S. operators of Group 2 airplanes is estimated to be $2,400, or $120 
per airplane, per inspection cycle.
    For Group 1 airplanes (approximately 191 U.S.-registered 
airplanes), it would take approximately 128 work hours per airplane to 
accomplish the proposed repair, at an average labor rate of $60 per 
work hour. Based on these figures, the cost impact of the proposed 
repair on U.S. operators of Group 1 airplanes is estimated to be 
$1,466,880, or $7,680 per airplane.
    For Group 2 airplanes (approximately 20 U.S.-registered airplanes), 
it would take approximately 64 work hours per airplane to accomplish 
the proposed repair, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of the proposed inspection on 
U.S. operators of Group 2 airplanes is estimated to be $76,800, or 
$3,840 per airplane.
    The cost impact figures discussed above are 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.
    Should an operator elect to accomplish the reinforcement of the 
door frame on a Group 1 airplane, it would take approximately 9 work 
hours per airplane to accomplish the reinforcement, at an average labor 
rate of $60 per work hour. Based on these figures, the cost impact of 
the reinforcement on a Group 1 airplane is estimated to be $540 per 
airplane.
    Should an operator elect to accomplish the reinforcement of the 
door frame on a Group 2 airplane, it would take approximately 5 work 
hours per airplane to accomplish the reinforcement, at an average labor 
rate of $60 per work hour. Based on these figures, the cost impact of 
the reinforcement on a Group 2 airplane is estimated to be $300 per 
airplane.

Regulatory Impact

    The regulations proposed herein would not have a substantial direct 
effect 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, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    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.

[[Page 37499]]

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 99-NM-377-AD.

    Applicability: Model 747 series airplanes, line numbers 1 
through 685 inclusive, 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 (g) 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 fatigue cracking of the frame web and doubler of the 
forward edge frame of main entry door number 1, which could result 
in inability of the edge frame to react door stop loads, and 
consequent rapid depressurization of the airplane, accomplish the 
following:

Initial Inspection: Compliance Time

    (a) At the time specified in paragraph (a)(1), (a)(2), (a)(3), 
or (a)(4); as applicable; accomplish the requirements of paragraphs 
(b) and (c) of this AD.
    (1) For airplanes that have accumulated fewer than 13,000 total 
flight cycles as of the effective date of this AD: Inspect prior to 
the accumulation of 13,000 total flight cycles, or within 1,500 
flight cycles after the effective date of this AD, whichever occurs 
later.
    (2) For airplanes that have accumulated 13,000 or more total 
flight cycles but fewer than 20,000 total flight cycles as of the 
effective date of this AD: Inspect prior to the accumulation of 
21,000 total flight cycles, or within 1,500 flight cycles after the 
effective date of this AD, whichever occurs first.
    (3) For airplanes that have accumulated 20,000 or more total 
flight cycles but fewer than 25,000 total flight cycles as of the 
effective date of this AD: Inspect prior to the accumulation of 
25,500 total flight cycles, or within 1,000 flight cycles after the 
effective date of this AD, whichever occurs first.
    (4) For airplanes that have accumulated 25,000 or more total 
flight cycles as of the effective date of this AD: Inspect within 
500 flight cycles after the effective date of this AD.

Initial Detailed Visual and High Frequency Eddy Current Inspections

    (b) Perform a detailed visual inspection and a high frequency 
eddy current inspection of the frame web, doubler, and inner chord 
of the forward edge door frame to detect cracking of main entry door 
number 1, in accordance with Boeing Service Bulletin 747-53A2417, 
Revision 1, dated July 23, 1998. For Group 1 airplanes (as 
identified in the service bulletin), accomplish the inspections on 
the left and right sides of the airplane. For Group 2 airplanes (as 
identified in the service bulletin), accomplish the inspections on 
the left side of the airplane only.

    Note 2: For the purposes of this AD, it is not necessary to 
count flight cycles accumulated at 2.0 pounds per square inch or 
less differential pressure.


    Note 3: Inspections, reinforcements, and repairs accomplished 
prior to the effective date of this AD in accordance with Boeing 
Alert Service Bulletin 747-53A2417, dated June 25, 1998, are 
considered acceptable for compliance with paragraph (b) of this AD.


    Note 4: 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.''

Repetitive Detailed Visual Inspections (No Terminating Action)

    (c) Remove the cover assembly for the body torque tube located 
between the door hinge attachments. Perform a detailed visual 
inspection to detect cracking of the aft side of the forward edge 
door frame web of main entry door number 1 in the exposed area from 
doorstop #2 [approximately water line (WL) 218] to doorstop #2 
(approximately WL 245) at body station 434. Pay particular attention 
to the row of fasteners that attach the frame web to the frame outer 
chord. After completing inspections, replace the cover assembly. 
Repeat the inspection thereafter at intervals not to exceed 3,000 
flight cycles.

    Note 5: The inspections required by paragraph (c) of this AD are 
not described in Boeing Service Bulletin 747-53A2417, Revision 1, 
dated July 23, 1998.


    Note 6: There is no terminating action currently available for 
the inspections required by paragraph (c) of this AD.

Repetitive Inspections/Reinforcement/Repair (No Cracks Detected)

    (d) If no crack is detected during the inspection required by 
paragraph (b) of this AD, prior to further flight, oversize fastener 
holes in accordance with Boeing Service Bulletin 747-53A2417, 
Revision 1, dated July 23, 1998, and accomplish the requirements of 
paragraph (d)(1), (d)(2), or (d)(3) of this AD.
    (1) Repeat the inspections specified in paragraph (b) of this AD 
one time within 3,000 flight cycles. Within 3,000 flight cycles 
after accomplishment of the repeat inspection, accomplish paragraph 
(d)(2) or (d)(3) of this AD.
    (2) Reinforce the door frame, in accordance with Figure 5 of the 
service bulletin. Thereafter, at intervals not to exceed 3,000 
flight cycles, perform a detailed visual inspection to detect cracks 
of the forward and aft side of the frame, in accordance with Figure 
6 of the service bulletin. Within 10,000 flight cycles after the 
reinforcement, accomplish the requirements of paragraph (d)(3) of 
this AD.
    (3) Accomplish the web replacement repair (``Terminating 
Action'') in accordance with the service bulletin. Such repair 
constitutes terminating action for the repetitive inspection 
requirements of paragraphs (d)(1) and (d)(2) of this AD.

Repair (Cracks Detected)

    (e) If any crack is detected during any inspection required by 
paragraph (b), (d)(1), or (d)(2) of this AD, prior to further 
flight, accomplish the repair (``Terminating Action'') in accordance 
with Boeing Service Bulletin 747-53A2417, Revision 1, dated July 23, 
1998. Such repair constitutes terminating action for the repetitive 
inspection requirements of paragraphs (d)(1) and (d)(2) of this AD.

Repair

    (f) If any cracking is detected during the inspection required 
by paragraph (c) 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; or 
in accordance with data meeting the type certification basis of the 
airplane approved by a Boeing Company Designated Engineering 
Representative (DER) who has been authorized by the Manager, Seattle 
ACO, to make such findings. For a repair method to be approved by 
the Manager, Seattle ACO, as required by this paragraph, the 
approval letter must specifically reference this AD.

Alternative Methods of Compliance

    (g) 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 7: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.


[[Page 37500]]



Special Flight Permits

    (h) 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 June 9, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-15190 Filed 6-14-00; 8:45 am]
BILLING CODE 4910-13-U