[Federal Register Volume 63, Number 11 (Friday, January 16, 1998)]
[Rules and Regulations]
[Pages 2593-2596]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-713]



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 Rules and Regulations
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  Federal Register / Vol. 63, No. 11 / Friday, January 16, 1998 / Rules 
and Regulations  

[[Page 2593]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-267-AD; Amendment 39-10284; AD 98-02-02]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes 
Equipped with Pratt & Whitney JT9D-3 and -7 Series Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to certain Boeing Model 747 series airplanes, that 
currently requires repetitive inspections for discrepancies of the 
forward engine mount bulkhead of the nacelle strut, and corrective 
action, if necessary. That AD also provides for optional terminating 
action for the repetitive inspections. For certain airplanes, this 
amendment adds repetitive inspections for discrepancies in the forward 
engine mount bulkhead and in the forward lower spar web, and corrective 
actions, if necessary. For other airplanes, this amendment adds a one-
time inspection to detect stop drilled cracks of the exterior of the 
forward engine mount chord, and replacement of the chord with a new 
chord, if necessary. This amendment also adds an additional optional 
terminating action for the repetitive inspections. This amendment is 
prompted by reports that fatigue cracking was found in an area adjacent 
to the inspection area specified in the existing AD. The actions 
specified in this AD are intended to detect and correct such fatigue 
cracking, which could lead to the failure of the forward engine mount 
bulkhead and consequent separation of the engine from the airplane.

DATES: Effective February 2, 1998.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of February 2, 1998.
    Comments for inclusion in the Rules Docket must be received on or 
before March 17, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 97-NM-267-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: Tamara L. Dow, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2771; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: On October 2, 1982, the FAA issued AD 82-22-
02, amendment 39-4476 (47 FR 46842, October 21, 1982), applicable to 
certain Boeing Model 747 series airplanes, to require repetitive 
inspections for discrepancies of the forward engine mount bulkhead of 
the nacelle strut, and corrective action, if necessary. That AD also 
provides for optional terminating action (installation of a new 
doubler) for the repetitive inspections. That action was prompted by 
reports of cracks in doublers that were installed as terminating action 
for AD 80-03-09, amendment 39-3832. The actions required by AD 82-22-02 
are intended to prevent failure of the forward engine mount bulkhead 
and possible separation of an engine from the airplane.

Actions Since Issuance of Previous Rule

    Since the issuance of AD 82-22-02, the FAA has received two reports 
of fatigue cracking in an area adjacent to the inspection area 
specified in that AD on the affected airplanes. In one incident, a 5-
inch long crack was found in the forward lower spar web aft of the 
bulkhead-to-firewall channel, and a 2-inch long crack was found in the 
bend radius of the chord of the forward mount bulkhead. These cracks 
occurred on the number 4 pylon. The airplane had accumulated 15,200 
total landings and 67,600 total flight hours. In the other incident, a 
2.5-inch crack was found in the chord of the forward mount bulkhead, 
and a 1.5-inch and 4-inch cracks were found in the forward lower spar 
web. These cracks occurred on the number 3 pylon.
    Such fatigue cracking, if not detected and corrected in a timely 
manner, could lead to the failure of the forward engine mount bulkhead 
and consequent separation of the engine from the airplane.

Discussion of Relevant Service Information

    Subsequent to the finding of this new cracking, the FAA reviewed 
and approved Boeing Alert Service Bulletin 747-54A2069, Revision 9, 
dated May 29, 1997. The revised alert service bulletin continues to 
describe procedures identical to those described in Revision 2 of the 
alert service bulletin (which was referenced in AD 82-22-02 as the 
appropriate source of service information). However, the revised alert 
service bulletin also describes new procedures for various repetitive 
inspections to detect discrepancies (i.e., cracks, damage, loose 
fasteners) in the forward engine mount bulkhead and in the forward 
lower spar web, and corrective actions, if necessary. The revised alert 
service bulletin also deletes the procedures for stop drilling cracks 
in the bulkhead chords.
    The FAA also has reviewed and approved the following Boeing service 
information:
     Alert Service Bulletin 747-54A2069, Revision 3, dated May 
23, 1980;
     Alert Service Bulletin 747-54A2069, Revision 4, dated 
November 26, 1980;
     Service Bulletin 747-54A2069, Revision 5, dated August 21, 
1981;
     Alert Service Bulletin 747-54A2069, Revision 6, dated 
October 22, 1982;
     Service Bulletin 747-54A2069, Revision 7, dated July 28, 
1988; and

[[Page 2594]]

     Service Bulletin 747-54A2069, Revision 8, dated June 9, 
1994.
    The inspection procedures specified in Revisions 3 through 8 of the 
service bulletin are similar to those specified in Revision 2 of the 
service bulletin. Therefore, the FAA has included in this AD references 
to these service bulletin revisions as additional sources of service 
information.

Explanation of Requirements of Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of this same type design, this AD 
supersedes AD 82-22-02 to continue to require repetitive inspections 
for discrepancies of the forward engine mount bulkhead of the nacelle 
strut, and corrective action, if necessary. This AD adds various 
repetitive inspections to detect discrepancies (i.e., cracks, damage, 
loose fasteners) in the forward engine mount bulkhead and in the 
forward lower spar web, and corrective actions, if necessary. This AD 
also adds an additional optional terminating action for the repetitive 
inspections. Unlike the requirements of AD 82-22-02, this AD does not 
permit further flight with cracks in the bulkhead chords.

Differences Between the AD and the Relevant Service Information

    Operators should note that, although the referenced service 
bulletins specify that the manufacturer must be contacted for 
disposition of certain conditions, this AD requires the repair or 
replacement of any cracked chord and/or web to be accomplished in 
accordance with a method approved by the FAA.
    The referenced service bulletins also specify that accomplishment 
of AD 95-10-16, amendment 39-9233 (59 FR 65733, December 21, 1994), is 
terminating action for the repetitive inspections. However, for 
airplanes on which the strut/wing modification required by AD 95-10-16 
has been accomplished, this AD requires a one-time detailed visual 
inspection to detect stop drilled cracks of the exterior of the forward 
engine mount chord. The FAA has determined that accomplishment of this 
inspection will ensure that all chords with stop drilled cracks are 
replaced.

Determination of Rule's Effective Date

    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 rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 97-NM-267-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    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 that it 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 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 removing amendment 39-4476 (47 FR 
46842, October 21, 1982), and by adding a new airworthiness directive 
(AD), amendment 39-10284, to read as follows:

98-02-02 Boeing: Amendment 39-10284. Docket 97-NM-267-AD. Supersedes 
AD 82-22-02, Amendment 39-4476.

    Applicability: Model 747 series airplanes; as listed in Boeing 
Alert Service Bulletin 747-54A2069, Revision 9, dated May 29, 1997; 
certificated in any category.

    Note 1: The airplanes specified in the applicability of this AD 
are the same as those specified in the applicability of AD 82-22-02.
    Note 2: 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 (f) 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 detect and correct fatigue cracking of the forward engine 
mount bulkhead, which

[[Page 2595]]

could lead to the failure of the forward engine mount bulkhead and 
consequent separation of the engine from the airplane, accomplish 
the following:

    (a) For airplanes on which the terminating action specified in 
AD 80-03-09, amendment 39-3832, has been accomplished: Within 300 
hours time-in-service after October 27, 1982 (the effective date of 
82-22-02, amendment 39-4476), accomplish paragraphs (a)(1), (a)(2), 
and (a)(3) of this AD. Repeat the inspections thereafter at 
intervals not to exceed 4,000 flight hours, until accomplishment of 
the inspections required by paragraphs (c)(1) and (c)(2) of this AD 
or the terminating action specified in paragraph (e) of this AD.
    (1) Perform an inspection to detect loose or missing fasteners 
of the fasteners attaching the forward engine mount bulkhead of the 
nacelle strut to the horizontal fire wall, in accordance with one of 
the following service bulletins listed below. If any loose or 
missing fastener is detected, prior to further flight, replace all 
fasteners in both rows of fasteners, in accordance with the service 
bulletin.
     Boeing Alert Service Bulletin 747-54A2069, Revision 2, 
dated February 1, 1980;
     Boeing Alert Service Bulletin 747-54A2069, Revision 3, 
dated May 23, 1980;
     Boeing Alert Service Bulletin 747-54A2069, Revision 4, 
dated November 26, 1980;
     Boeing Service Bulletin 747-54A2069, Revision 5, dated 
August 21, 1981;
     Boeing Alert Service Bulletin 747-54A2069, Revision 6, 
dated October 22, 1982;
     Boeing Service Bulletin 747-54A2069, Revision 7, dated 
July 28, 1988;
     Boeing Service Bulletin 747-54A2069, Revision 8, dated 
June 9, 1994; or
     Boeing Alert Service Bulletin 747-54A2069, Revision 9, 
dated May 29, 1997.
    (2) Remove by hand the protective coating of the area to be 
penetrant inspected using 400 grit or equivalent abrasive, and 
perform a penetrant inspection to detect cracks of the bulkhead 
chords, in accordance with one of the service bulletins listed 
below:
     Boeing Alert Service Bulletin 747-54A2069, Revision 2, 
dated February 1, 1980;
     Boeing Alert Service Bulletin 747-54A2069, Revision 3, 
dated May 23, 1980;
     Boeing Alert Service Bulletin 747-54A2069, Revision 4, 
dated November 26, 1980;
     Boeing Service Bulletin 747-54A2069, Revision 5, dated 
August 21, 1981;
     Boeing Alert Service Bulletin 747-54A2069, Revision 6, 
dated October 22, 1982;
     Boeing Service Bulletin 747-54A2069, Revision 7, dated 
July 28, 1988;
     Boeing Service Bulletin 747-54A2069, Revision 8, dated 
June 9, 1994; or
     Boeing Alert Service Bulletin 747-54A2069, Revision 9, 
dated May 29, 1997.
    (i) If any crack is detected on the outside radius of the chord, 
and it is within the limits specified in the service bulletin, prior 
to further flight, perform a penetrant inspection to detect cracks 
on the inside radius of the chord, in accordance with the service 
bulletin.
    (A) If any crack is detected on the inside radius of the chord, 
and it is within the limits specified in the service bulletin, prior 
to further flight, rework the cracked part in accordance with the 
service bulletin. Repeat the penetrant inspection required by 
paragraph (a)(2) of this AD thereafter at intervals not to exceed 
600 flight hours, until accomplishment of the inspections required 
by paragraphs (c)(1) and (c)(2) of this AD or the terminating action 
specified in paragraph (e) of this AD.
    (B) If any crack is detected on the inside radius of the chord, 
and it is outside the limits specified in the service bulletin, 
prior to further flight, replace the cracked part with a new part, 
in accordance with a method approved by the Manager, Seattle 
Aircraft Certification Office (ACO), FAA, Transport Airplane 
Directorate.
    (ii) If any crack is detected on the outside radius of the 
chord, and it is outside the limits specified in the service 
bulletin, prior to further flight, replace the cracked part with a 
new part in accordance with a method approved by Seattle ACO.
    (3) Perform an inspection to detect evidence of looseness of the 
fasteners attaching the forward engine mount fittings to the strut 
bulkhead. If any loose fastener is detected, prior to further 
flight, replace it with a new fastener.
    (b) For airplanes on which only loose fasteners have been 
replaced as required by telegraphic AD T79-NW-21, amendment 39-3687: 
Within 600 hours time-in-service after October 27, 1982, replace all 
fasteners in both rows of fasteners with new fasteners in accordance 
with one of the service bulletins listed below:
     Boeing Alert Service Bulletin 747-54A2069, Revision 2, 
dated February 1, 1980;
     Boeing Alert Service Bulletin 747-54A2069, Revision 3, 
dated May 23, 1980;
     Boeing Alert Service Bulletin 747-54A2069, Revision 4, 
dated November 26, 1980;
     Boeing Service Bulletin 747-54A2069, Revision 5, dated 
August 21, 1981;
     Boeing Alert Service Bulletin 747-54A2069, Revision 6, 
dated October 22, 1982;
     Boeing Service Bulletin 747-54A2069, Revision 7, dated 
July 28, 1988;
     Boeing Service Bulletin 747-54A2069, Revision 8, dated 
June 9, 1994; or
     Boeing Alert Service Bulletin 747-54A2069, Revision 9, 
dated May 29, 1997.
    (c) For airplanes on which the strut/wing modification required 
by AD 95-10-16, amendment 39-9233, has not been accomplished: Within 
90 days after the effective date of this AD, accomplish paragraphs 
(c)(1) and (c)(2) of this AD.
    (1) Perform various inspections to detect discrepancies (i.e., 
cracks, damage, loose fasteners) in the forward engine mount 
bulkhead and in the forward lower spar web, in accordance with 
Figure 1 of Boeing Alert Service Bulletin 747-54A2069, Revision 9, 
dated May 29, 1997. If any discrepancy is detected, prior to further 
flight, perform the applicable corrective action in accordance with 
Figure 1 of the alert service bulletin; except the repair or 
replacement of any cracked chord and/or web shall be accomplished in 
accordance with a method approved by the Manager, Seattle ACO. 
Repeat the inspections thereafter at intervals not to exceed 4,000 
flight hours.
    (2) Perform an inspection to detect evidence of looseness of the 
fasteners attaching the forward engine mount fittings to the strut 
bulkhead. If any loose fastener is detected, prior to further 
flight, replace it with a new fastener in accordance with Boeing 
Document D6-13592, ``747 Structural Repair Manual (SRM),'' Chapter 
51, Subject 51-30-04, Revision 8, dated September 5, 1997.
    (d) For airplanes on which the strut/wing modification required 
by AD 95-10-16, amendment 39-9233, has been accomplished: Within 90 
days after the effective date of this AD, perform a detailed visual 
inspection to detect stop drilled cracks of the exterior of the 
forward engine mount chord. Inspect to the height of the engine 
mount fitting (approximately 12 inches). If any crack (including a 
stop drilled crack) is detected, prior to further flight, replace 
the chord with a new chord in accordance with a method approved by 
the Manager, Seattle ACO.

    Note 3: Inspections required by AD 94-17-17, amendment 39-9012, 
are similar and somewhat overlap the inspections required by this 
AD.

    (e) Accomplishment of either paragraphs (e)(1) and (e)(2), or 
paragraphs (e)(2) and (e)(3) of this AD constitutes terminating 
action for the requirements of this AD.
    (1) Modify the fasteners and install a doubler on the forward 
lower spar web, or replace the doubler of the forward lower spar web 
with a new doubler, in accordance with Figure 2 or Figure 3, as 
applicable, of Boeing Alert Service Bulletin 747-54A2069, Revision 
6, dated October 22, 1982; Boeing Service Bulletin 747-54A2069, 
Revision 7, dated July 28, 1988; Boeing Service Bulletin 747-
54A2069, Revision 8, dated June 9, 1994; or Boeing Alert Service 
Bulletin 747-54A2069, Revision 9, dated May 29, 1997.
    (2) Replace any cracked forward engine mount bulkhead chord with 
a new chord, and replace any cracked forward lower spar web with a 
new web, in accordance with a method approved by the Manager, 
Seattle ACO.
    (3) Modify the nacelle strut and wing structure in accordance 
with Boeing Alert Service Bulletin 747-54A2159, dated November 3, 
1994; Revision 1, dated June 1, 1995; or Revision 2, dated March 14, 
1996.
    (f) 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 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (g) 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.
    (h) Except as provided in paragraphs (a)(2)(i)(B), (a)(2)(ii), 
(c)(1), (c)(2), (d), and

[[Page 2596]]

(e)(2) of this AD, the actions shall be done in accordance with the 
following Boeing service bulletins, as applicable, which contain the 
specified effective pages:

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                           Revision level                                               
   Service bulletin referenced and date                       Page No.                     shown on page                 Date shown on page             
--------------------------------------------------------------------------------------------------------------------------------------------------------
Alert Service Bulletin 747-54A2069,        1-9                                                         2   February 1, 1980.                            
 Revision 2, February 1, 1980.                                                                                                                          
Alert Service Bulletin 747-54A2069,        1-7                                                         3   May 23, 1980.                                
 Revision 3, May 23, 1980.                 8                                                           2   February 1, 1980.                            
Alert Service Bulletin 747-54A2069,        1, 9, 10, 12, 19-21                                         4   November 26, 1980.                           
 Revision 4, November 26, 1980.            2-7, 11, 13-18                                              3   May 23, 1980.                                
                                           8                                                           2   February 1, 1980.                            
Service Bulletin 747-54A2069, Revision 5,  1-7, 9, 10, 17                                              5   August 21, 1980.                             
 August 21, 1981.                          8                                                           2   February 1, 1980.                            
                                           11, 13-16, 18                                               3   May 23, 1980.                                
                                           12, 19-21                                                   4   November 26, 1980.                           
Alert Service Bulletin 747-54A2069,        1-28                                                        6   October 22, 1982.                            
 Revision 6, October 22, 1982.                                                                                                                          
Service Bulletin 747-54A2069, Revision 7,  1-5, 7-16, 24, 28                                           7   July 28, 1988.                               
 July 28, 1988.                                                                                                                                         
                                           6, 17-23, 25-27                                             6   October 22, 1982.                            
Service Bulletin 747-54A2069, Revision 8,  1-28                                                        8   June 9, 1994.                                
 June 9, 1994.                                                                                                                                          
Alert Service Bulletin 747-54A2069,        1-28                                                        9   May 29, 1997.                                
 Revision 9, May 29, 1997.                                                                                                                              
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    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.
    (i) This amendment becomes effective on February 2, 1998.

    Issued in Renton, Washington, on January 6, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-713 Filed 1-15-98; 8:45 am]
BILLING CODE 4910-13-U