[Federal Register Volume 64, Number 156 (Friday, August 13, 1999)]
[Rules and Regulations]
[Pages 44110-44112]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-20501]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-275-AD; Amendment 39-11251; AD 99-17-02]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 777 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment adopts a new airworthiness directive (AD),
applicable to certain Boeing Model 777 series airplanes, that requires
repetitive inspections of the safety spring wear plate doublers
attached to the auxiliary power unit (APU) firewall, measurement of
wear of the doublers, and follow-on actions, if necessary. For certain
airplanes, this amendment also requires a one-time inspection to detect
improper clearance between the safety spring wear plate doubler and the
APU firewall, and corrective action, if necessary. This amendment also
provides for optional terminating action for the repetitive
inspections. This amendment is prompted by reports indicating that
excessive wear was found on the safety spring wear plate doublers on
the APU firewall of Boeing Model 777 series airplanes. The actions
specified by this AD are intended to detect and correct wear of the
safety spring wear plate doublers on the APU firewall, which could
result in a hole in the APU firewall, and consequent decreased fire
protection capability.
DATES: Effective September 17, 1999.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of September 17, 1999.
ADDRESSES: 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 Federal
Aviation Administration (FAA), Transport Airplane Directorate, Rules
Docket, 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: Ed Hormel, Aerospace Engineer,
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate,
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (425) 227-2681; fax (425) 227-1181.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) to include an airworthiness
directive (AD) that is applicable to certain Boeing Model 777 series
airplanes was published as a supplemental notice of proposed rulemaking
(NPRM) in the Federal Register on April 8, 1999 (64 FR 17130). That
action proposed to require repetitive inspections of the safety spring
wear plate doublers attached to the auxiliary power unit (APU)
firewall, measurement of wear of the doublers, and follow-on actions,
if necessary. For certain airplanes, that action also proposed to
require a one-time inspection to detect improper clearance between the
safety spring wear plate doubler and the APU firewall, and corrective
action, if necessary. That action also provided for optional
terminating action for the repetitive inspections.
Comments
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
Support for the Proposal
One commenter supports the proposed rule.
Request for Extension of the Compliance Time
One commenter requests that the compliance time for the actions
specified by paragraphs (a), (b), and (c) of the proposed AD be
extended. The commenter states that it operates 34 airplanes affected
by the proposed rule, including airplanes that have accumulated as many
as 15,000 total flight hours. The commenter states that it has begun
accomplishing the terminating action, and thus far, none of the removed
wear plates show wear levels approaching penetration. Although the
commenter supports the decision to mandate Boeing Alert Service
Bulletin 777-53A0018, Revision 1, dated February 11, 1999, it feels
that the inspection compliance times specified in paragraphs (a), (b),
and (c) of the proposal are unnecessarily conservative.
The FAA does not concur with the commenter's request to extend the
compliance time. In developing an appropriate compliance time for this
action, the FAA considered the safety implications, parts availability,
and normal maintenance schedules for timely accomplishment of the
modification. In consideration of these items, as well as the
variability in the reported wear rate of the safety spring wear plate
doublers attached to the APU firewall, the FAA has determined that the
compliance times specified in paragraphs (a), (b), and (c) of the AD
will not place an undue hardship on the majority of affected operators,
and an acceptable level of safety can be maintained. No change to the
final rule is necessary.
Explanation of Changes Made to the Applicability
The final rule has been revised to correct the applicability of the
AD. In the preamble to the supplemental NPRM, the FAA discussed the
difference between the effectivity listing of the alert service
bulletin and the applicability of the AD. The supplemental NPRM stated
that Model 777 series airplanes after line number 156 have stainless
steel wear plate doublers installed prior to delivery. Since the
issuance of the supplemental NPRM, the FAA has determined that there
are four airplanes having line numbers less than 157 (line numbers 94,
102, 104, and 120) that had the stainless
[[Page 44111]]
steel wear plate doublers installed prior to delivery. The alert
service bulletin identifies airplanes having line numbers 94, 102, 104,
120, and 157 through 183 inclusive, as Group 3 airplanes. None of these
airplanes would be subject to the unsafe condition described above;
therefore, the applicability of the final rule has been revised to
include only Groups 1 and 2 airplanes, as listed in the alert service
bulletin. The four affected airplanes were not included in the cost
impact in the proposed rule; therefore, no change is required to the
cost impact.
Conclusion
After careful review of the available data, including the comments
noted above, the FAA has determined that air safety and the public
interest require the adoption of the rule with the changes previously
described. The FAA has determined that these changes will neither
increase the economic burden on any operator nor increase the scope of
the AD.
Cost Impact
There are approximately 152 airplanes of the affected design in the
worldwide fleet. The FAA estimates that 35 airplanes of U.S. registry
will be affected by this AD.
It will take approximately 2 work hours per airplane to accomplish
the required inspection to detect wear of the safety spring wear plate
doublers, at an average labor rate of $60 per work hour. Based on these
figures, the cost impact of this inspection required by this AD on U.S.
operators is estimated to be $4,200, or $120 per airplane, per
inspection cycle.
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.
Should an operator be required to accomplish the temporary repair,
it will take approximately 2 work hours per airplane to accomplish the
repair, at an average labor rate of $60 per work hour. Based on these
figures, the cost impact of the temporary repair is estimated to be
$120 per airplane.
Should an operator be required to accomplish the inspection to
detect improper clearance between the safety spring wear plate doubler
and the APU firewall, it will take approximately 1 work hour per
airplane to accomplish the inspection, at an average labor rate of $60
per work hour. Based on these figures, the cost impact of this
inspection is estimated to be $60 per airplane.
Should an operator be required or elect to accomplish the
replacement of the wear plate doublers, it will take approximately 3
work hours per airplane to accomplish the replacement, at an average
labor rate of $60 per work hour. Required parts, if acquired from the
manufacturer, will cost approximately $193 per airplane. Based on these
figures, the cost impact of replacement of the wear plate doublers is
estimated to be $373 per airplane.
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.
For the reasons discussed above, I certify that this action (1) is
not a ``significant regulatory action'' under Executive Order 12866;
(2) is not a ``significant rule'' under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action
and it is contained in the Rules Docket. A copy of it 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 adding the following new
airworthiness directive:
99-17-02 Boeing: Amendment 39-11251. Docket 98-NM-275-AD.
Applicability: Model 777 series airplanes listed as Groups 1 and
2 airplanes in Boeing Service Bulletin 777-53A0018, Revision 1,
dated February 11, 1999; 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 (h) 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 wear of the safety spring wear plate
doublers on the auxiliary power unit (APU) firewall, which could
result in a hole in the APU firewall, and consequent decreased fire
protection capability, accomplish the following:
Initial Inspection
(a) Perform a visual inspection of the two safety spring wear
plate doublers on the APU firewall, and measure any wear of the
doublers, in accordance with Boeing Service Bulletin 777-53A0018,
Revision 1, dated February 11, 1999, at the time specified in
paragraph (a)(1), (a)(2), or (a)(3) of this AD, as applicable.
(1) For airplanes that have accumulated 6,000 total flight hours
or less as of the effective date of this AD: Inspect and measure
prior to the accumulation of 6,300 total flight hours.
(2) For airplanes that have accumulated more than 6,000 but less
than 10,000 total flight hours as of the effective date of this AD:
Inspect and measure within 30 days after the effective date of this
AD.
(3) For airplanes that have accumulated 10,000 total flight
hours or more as of the effective date of this AD: Inspect and
measure within 10 days after the effective date of this AD.
Note 2: Inspections, repairs, and modifications accomplished
prior to the effective date of this AD in accordance with Boeing
Alert Service Bulletin 777-53A0018, dated June 29, 1998, are
considered acceptable for compliance with this AD, provided that the
actions required by paragraph (f) of this AD, as applicable, are
accomplished in accordance with Boeing Service Bulletin 777-53A0018,
Revision 1, dated February 11, 1999.
[[Page 44112]]
Repetitive Inspections
(b) If, during the inspection required by paragraph (a) of this
AD, the wear on each doubler measures less than 0.045 inch, repeat
the inspection and measurement required by paragraph (a) of this AD
thereafter at intervals not to exceed 60 days, in accordance with
Boeing Service Bulletin 777-53A0018, Revision 1, dated February 11,
1999; until paragraph (g) of this AD has been accomplished.
(c) If, during the inspection required by paragraph (a) of this
AD, the wear on either doubler measures greater than or equal to
0.045 inch, but does not penetrate into or through the APU firewall:
Repeat the inspection and measurement required by paragraph (a) of
this AD thereafter at intervals not to exceed 30 days, in accordance
with Boeing Service Bulletin 777-53A0018, Revision 1, dated February
11, 1999; until paragraph (g) of this AD has been accomplished.
Corrective Actions
(d) If, during the inspection required by paragraph (a) of this
AD, any wear penetrates through either doubler and into or through
the APU firewall: Within 20 days after detection of the wear,
accomplish either paragraph (d)(1) or (d)(2) of this AD in
accordance with Boeing Service Bulletin 777-53A0018, Revision 1,
dated February 11, 1999.
(1) Install a temporary stainless steel patch on both doublers,
and within 4,000 flight cycles after installation of the temporary
patch, accomplish the requirements of paragraph (e) of this AD.
(2) Accomplish the requirements of paragraph (e) of this AD.
(e) For airplanes on which wear is detected that penetrates
through either doubler and into or through the APU firewall:
Accomplish the requirements of paragraphs (e)(1) and (e)(2) of this
AD at the time specified in paragraph (d) of this AD, as applicable.
(1) Repair the damage to the APU firewall in accordance with a
method approved by the Manager, Seattle Aircraft Certification
Office (ACO), FAA, Transport Airplane Directorate.
(2) Replace both existing wear plate doublers of the APU
firewall with new stainless steel wear plate doublers in accordance
with Boeing Service Bulletin 777-53A0018, Revision 1, dated February
11, 1999. Such replacement constitutes terminating action for the
repetitive inspection requirements of paragraphs (b) and (c) of this
AD.
One-Time Inspection
(f) For airplanes having L/N 001 through 037 inclusive that have
been modified prior to the effective date of this AD in accordance
with Boeing Alert Service Bulletin 777-53A0018, dated June 29, 1998:
Within 4 years after the effective date of this AD, perform a one-
time visual inspection to detect improper clearance between the
safety spring wear plate doublers and the APU firewall, in
accordance with Boeing Service Bulletin 777-53A0018, Revision 1,
dated February 11, 1999.
(1) If the doublers are not in contact with the chemically
milled pocket of the APU firewall, no further action is required by
this paragraph.
(2) If the doublers are in contact with the chemically milled
pocket of the APU firewall, prior to further flight, install shims
between the safety spring wear plate doublers and the APU firewall,
in accordance with Part 6 of the Accomplishment Instructions of the
service bulletin.
Optional Terminating Action
(g) Replacement of the existing wear plate doublers of the APU
firewall with new stainless steel wear plate doublers, in accordance
with Boeing Service Bulletin 777-53A0018, Revision 1, dated February
11, 1999, constitutes terminating action for the repetitive
inspection requirements of paragraphs (b) and (c) of this AD.
Alternative Methods of Compliance
(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 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
(i) 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.
Incorporation by Reference
(j) Except as provided by paragraph (e)(1) of this AD, the
actions shall be done in accordance with Boeing Service Bulletin
777-53A0018, Revision 1, dated February 11, 1999. 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 September 17, 1999.
Issued in Renton, Washington, on August 4, 1999.
D. L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-20501 Filed 8-12-99; 8:45 am]
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