[Federal Register Volume 63, Number 31 (Tuesday, February 17, 1998)]
[Rules and Regulations]
[Pages 7693-7696]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-3635]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 96-NM-78-AD; Amendment 39-10341; AD 98-04-29]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 727 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 all Boeing Model 727 series airplanes, that requires a
one-time visual inspection of the manual extension gearbox assembly of
the main landing gear (MLG) to detect whether certain gearbox housings
have been installed; repetitive dye penetrant inspections of these
housings to determine whether cracking has occurred; and ultimately,
replacement of these housings with correct housings. This amendment is
prompted by a report indicating that a manual gearbox assembly which
contained an incorrect housing was installed on a Model 727 series
airplane. The actions specified by this AD are intended to detect the
installation of manual extension gearbox assemblies with incorrect
housings. This condition, if not corrected, could reduce the structural
integrity of the manual extension gearbox assembly, and ultimately
result in an inability to lock the MLG in a down position during
landing.
DATES: Effective March 24, 1998.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of March 24, 1998.
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: Walter M. Sippel, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office,
1601 Lind Avenue, SW., Renton, Washington; telephone (425) 227-2774;
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 all Boeing Model 727 series
airplanes was published in the Federal Register on October 3, 1996 (61
FR 51621). That action proposed to require a one-time visual inspection
of the manual extension gearbox assembly of the main landing gear (MLG)
to detect whether this assembly contains the correct left and right
gearbox housings/housing assemblies. If incorrect housings/housing
assemblies are installed, that action also proposed to require
repetitive dye penetrant inspections of these housings to determine
whether cracking has occurred; and ultimately, replacement of these
housings with correct housings.
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
Three commenters support the proposed rule.
Request to Withdraw the Proposal
Several commenters state that the proposed AD is unnecessary
because AD 79-04-01 R3, amendment 39-4000 (45 FR 84014, December 22,
1980), addresses the problem, thus the proposed AD only duplicates time
and effort. One of these commenters points out that the ``incomplete
information . . .'' of Boeing Overhaul Manual 32-35-01 (referred to in
the Discussion Section of the preamble of the proposed AD) is ``a very
gray area.'' This commenter contends that almost all overhaul manuals
contain ``incomplete information,'' even when components are affected
by AD's. The commenters assert that it is the responsibility of the
operators and component vendors to determine which parts are affected
by an AD. Two of these commenters state that all of their gearbox
housings comply with the requirements of AD 79-01-04 R3.
The FAA does not concur that the proposed AD should be withdrawn.
The FAA acknowledges that, even though an overhaul manual may contain
[[Page 7694]]
incomplete information, operators are responsible for the overall
airworthiness of the airplane. In addition, component vendors should be
cognizant of AD's that affect parts they are overhauling.
However, as explained in the Discussion section of the preamble of
the proposed AD, the FAA has received a report indicating that a manual
extension gearbox assembly for the MLG on a Boeing Model 727 series
airplane had been replaced with a modified gearbox assembly that did
not comply with AD 79-01-04 R3. In light of this report and the fact
that the manufacturer's overhaul manual contained incomplete
information for a period of time, the FAA finds that there currently
may be other Model 727 series airplanes in service that are operating
with incorrect gearbox housing/housing assemblies installed. Therefore,
the FAA has determined that a one-time visual inspection of the manual
extension gearbox assembly of the main landing gear (MLG) is necessary
to detect whether or not these discrepant housings have been installed.
Request to Extend Compliance Time for One-Time Visual Inspection
One commenter requests that the compliance time for accomplishing
the proposed one-time visual inspection be extended from the proposed 6
months to the first ``C'' check after the effective date of the AD. The
commenter points out that it has found no cracked gearbox housing since
accomplishment of AD 79-04-01 R3.
The FAA does not concur. 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 visual inspection. In consideration of these
items, as well as the report indicating that a manual gearbox assembly
containing an incorrect housing had been installed on an airplane in
service, the FAA has determined that a 6-month compliance time is
appropriate.
Request to Extend Compliance Time for Initial Dye Penetrant
Inspection
One commenter requests that the compliance time for accomplishing
the dye penetrant inspection required by paragraph (c) of the proposed
AD be extended from the proposed ``prior to further flight'' to
``within 100 hours time-in-service or 50 landings, whichever occurs
first.'' The commenter states that the proposed compliance time is not
justified because the FAA has not received recent reports of incorrect
housing/housing assemblies that have been cracked. This commenter also
states that it would have to special schedule its fleet of airplanes to
accomplish this inspection within the proposed compliance time; this
would entail considerable additional expenses and schedule disruptions.
The FAA concurs partially. The FAA finds that stress corrosion
cracking in the vertical support attaching lugs of the MLG manual
extension-gearbox housing is caused by the combined action of corrosion
and stress, either external (applied) or internal (residual). It is
difficult to predict when stress corrosion cracking will occur because
corrosion is influenced by unpredictable factors, such as the operating
environment, maintenance, and the passage of time. If those housings/
housing assemblies are still installed on airplanes more than 17 years
after AD 79-04-01 R3 was issued, there is a greater likelihood that
stress corrosion cracking exists; therefore, the FAA finds that
accomplishment of a dye penetrant inspection prior to further flight
following accomplishment of the initial visual inspection is warranted.
However, the FAA's intent is that the dye penetrant inspection be
conducted during a regularly schedule maintenance visit for the
majority of the affected fleet, when the airplanes would be located at
a base where special equipment and trained personnel would be readily
available, if necessary. The FAA finds that in lieu of accomplishing a
dye penetrant inspection, an operator may choose to replace the
discrepant part with an updated part prior to further flight following
accomplishment of the initial visual inspection. Therefore, paragraph
(c) of the final rule has been revised to provide operators with this
option.
Request to Revise Dye Penetrant Inspection Requirement
One commenter requests that operators be advised of where the
incorrect gear boxes were found and of the source that obtained them.
Subsequently, the discrepant gear boxes could be tracked and the
proposed inspection requirements could be limited to those operators
that received the discrepant housings from the suspect sources. The
commenter also suggests that the initial visual inspection be
accomplished within 300 landings and repeated at intervals not to
exceed 6 months, and suggests that the replacement be accomplished
within 18 months.
The FAA does not concur. The FAA is unable to determine all sources
of discrepant housings. Therefore, the FAA finds that the proposed one-
time visual inspection is necessary to determine whether certain
gearbox housings have been installed. In addition, the FAA finds that a
compliance time based on a number of landings is not acceptable
because, as discussed previously, it is difficult to predict when
stress corrosion cracking will occur.
Request to Revise Applicability of the Proposal
Two commenters request that the applicability of the proposed AD be
revised to exclude airplanes whose operators are confident of their
gearbox installations or have internal procedures to ensure that only
correct housing/housing assemblies are installed in accordance with AD
79-04-01 R3.
The FAA does not concur. A one-time visual inspection to confirm
the presence of correct housings should not pose an undue burden to
operators. If an operator chooses to review its available records,
however, to determine that incorrect manual extension gearbox
assemblies have not been installed, the operator may request approval
of an alternative method of compliance in accordance with the
provisions of paragraph (d) of this AD.
Request to Revise Table 2 of the Proposal
One commenter requests that Table 2 of the proposed AD, which lists
the part numbers of correct replacement housings and housing
assemblies, be revised to include the Boeing part number of the die
forging from which these parts could be made. (Not all of the correct
parts are made from this forging.) The commenter points out that the
part number on this die forging is easily ascertained and permanent,
unlike the numbers on the housings/housing assemblies currently listed
in Table 2. For the reasons the commenter states, the FAA concurs and
has revised Table 2, as requested. In addition, because all the
incorrect housings/housing assemblies are made from a certain die
forging, the FAA has added the Boeing part number of that forging to
Table 1, which lists the part numbers of incorrect housing and housing
assemblies.
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.
[[Page 7695]]
Cost Impact
There are approximately 1,560 Boeing Model 727 series airplanes of
the affected design in the worldwide fleet. The FAA estimates that
1,054 airplanes of U.S. registry will be affected by this AD.
The FAA estimates that it will take approximately 2 work hours per
airplane to accomplish the required one-time visual inspection, at an
average labor rate of $60 per work hour. Based on these figures, the
cost impact of the AD on U.S. operators is estimated to be $126,480, or
$120 per airplane.
Should a dye penetrant inspection need to be performed, the FAA
estimates that each inspection will take approximately 20 work hours
per airplane, at an average labor rate of $60 per work hour. Based on
these figures, the cost impact of the proposed dye penetrant inspection
on U.S. operators is estimated to be $1,200 per airplane, per
inspection.
Should parts have to be replaced, the FAA estimates that it will
take approximately 16 work hours per airplane to accomplish the
replacement, at an average labor rate of $60 per work hour. Replacement
parts will cost approximately $4,000 per housing. Based on these
figures, the cost impact of replacement of parts on U.S. operators is
estimated to be $4,960 per airplane if one housing is to be replaced,
and $8,960 if both housings are to be replaced.
The cost impact figures discussed above are based on assumptions
that no operator has yet accomplished any of the requirements of this
AD action, and that no operator will accomplish those actions in the
future if this AD were not adopted.
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:
98-04-29 Boeing: Amendment 39-10341. Docket 96-NM-78-AD.
Applicability: All Model 727 airplanes, 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 (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 detect the installation of manual extension gearbox
assemblies that do not contain required gearbox housings/housing
assemblies, and ultimately could result in the inability of the
flight crew to lock the main landing gear (MLG) in the down position
during landing, accomplish the following:
(a) Within 6 months after the effective date of this AD,
visually inspect the manual extension gearbox assembly of the MLG,
in accordance with Boeing Service Bulletin 727-32-279, dated June
22, 1979, to determine whether left and right gearbox housings/
housing assemblies having Boeing part numbers listed in Table 1 of
this AD are installed.
Note 2: If the part number is not visible, a conductivity test
may be performed to determine the type of housing material.
Incorrect housings are made of 7079-T6 aluminum; correct housings
are made of 7075-T73 aluminum.
Table 1.--Boeing Part Numbers of Incorrect Housings and Housing
Assemblies
------------------------------------------------------------------------
Housings* Housing assemblies
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65-27485-3......................... 65-27485-1
65-27485-4......................... 65-27485-2
65-27485-9......................... 65-27485-7
65-27485-10........................ 65-27485-8
------------------------------------------------------------------------
* All housings are made from die forging 65-27485-6.
(b) If none of the incorrect housings/housing assemblies are
installed, no further action is required by this AD.
(c) If any of the incorrect housings/housing assemblies are
installed, prior to further flight, accomplish either paragraph
(c)(1) or (c)(2) of this AD.
(1) Perform a dye penetrant inspection to detect cracking of the
housing, in accordance with Boeing Service Bulletin 727-32-279,
dated June 22, 1979.
(i) If no cracking is detected during the dye penetrant
inspection, the incorrect housing/housing assembly may be
reinstalled. Thereafter, accomplish the actions required by
paragraphs (c)(1)(i)(A) and (c)(1)(i)(B) of this AD.
(A) After reinstallation, repeat the dye penetrant inspection at
intervals not to exceed 9 months.
(B) Within 18 months after the initial dye penetrant inspection
required by paragraph (c)(1) of this AD is accomplished, replace the
housing/housing assemblies with parts having an applicable Boeing
part number listed in Table 2 of this AD, in accordance with the
service bulletin. This replacement constitutes terminating action
for the repetitive dye penetrant inspections required by paragraph
(c)(1)(i)(A) of this AD and, thereafter, no further action is
required by this AD.
(ii) If any cracking is detected during the dye penetrant
inspection, prior to further flight, replace the housing/housing
assemblies with parts having an applicable Boeing part number listed
in Table 2 of this AD, in accordance with the service bulletin. This
replacement constitutes terminating action for the repetitive dye
penetrant inspections required by paragraph (c)(1)(i)(A) of this AD
and, thereafter, no further action is required by this AD.
(2) Replace the discrepant part with an applicable Boeing part
number listed in Table 2 of this AD, in accordance with the service
bulletin. Thereafter, no further action is required by this AD.
Note 3: This AD prohibits the reinstallation (or installation)
of any housing that is cracked, even though the service bulletin
provides instructions for reinstallation of a cracked, incorrect
housing in certain circumstances.
[[Page 7696]]
Table 2.--Boeing Part Numbers of Correct Replacement Housings and
Housing Assemblies
------------------------------------------------------------------------
Housings* Housing assemblies
------------------------------------------------------------------------
65-27485-13........................ 65-27485-11
65-27485-14........................ 65-27485-12
65-27485-19........................ 65-27485-17
65-27485-20........................ 65-27485-18
------------------------------------------------------------------------
* Housings may be made from die forging 65-27485-15.
Note 4: Although not listed in the service bulletin or in AD 79-
04-01 R3 (amendment 39-4000), housings/housing assemblies having
part numbers 65-27485-19/65-27485-17 and 65-27485-20/65-27485-18 are
fully interchangeable with those having part numbers 65-27485-13/65-
27485-11 and 65-27485-14/65-27485-12.
(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 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 5: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
(e) 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.
(f) The inspections and replacement of parts shall be done in
accordance with Boeing Service Bulletin 727-32-279, dated June 22,
1979. 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.
(g) This amendment becomes effective on March 24, 1998.
Issued in Renton, Washington, on February 6, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 98-3635 Filed 2-13-98; 8:45 am]
BILLING CODE 4910-13-U
