[Federal Register Volume 61, Number 191 (Tuesday, October 1, 1996)]
[Proposed Rules]
[Pages 51250-51255]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-25040]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 95-NM-223-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 727 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Supplemental notice of proposed rulemaking; reopening of
comment period.
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SUMMARY: This document revises an earlier proposed airworthiness
directive (AD), applicable to all Boeing Model 727 series airplanes,
that would have superseded a previously issued AD that currently
requires inspections to detect cracking of the actuator rib fitting of
the inboard door of the main landing gear (MLG); and rework or
replacement of any cracked fitting. The proposed action would have
required inspections to detect cracking in an expanded area of the
actuator rib fitting, and various follow-on actions. That action was
prompted a report of a fractured rib fitting that had been reworked in
accordance with the existing AD. This new proposed action would expand
the area of inspection even further than what was previously proposed,
and would supersede another AD that requires actions related to the
addressed area of the MLG. The actions specified by the proposed AD are
intended to prevent damage to the airplane caused by a failure of the
landing gear to extend due to a fractured rib fitting.
DATES: Comments must be received by October 24, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 95-NM-223-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: Walter Sippel, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office,
1601 Lind Avenue, SW., Renton, Washington; telephone (206) 227-2774;
fax (206) 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 95-NM-223-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-103, Attention: Rules
Docket No.
[[Page 51251]]
95-NM-223-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.
Discussion
A proposal to amend part 39 of the Federal Aviation Regulations (14
CFR part 39) to add an airworthiness directive (AD), applicable to all
Boeing Model 727 series airplanes, was published as a notice of
proposed rulemaking (NPRM) in the Federal Register on April 1, 1996 (61
FR 14271). That NPRM would have superseded AD 90-02-19, amendment 39-
6433 (55 FR 601, January 8, 1990), which currently requires inspections
to detect cracking of the actuator rib fitting of the inboard door of
the main landing gear (MLG); and rework or replacement of any cracked
fitting with a reworked or new fitting. That AD was prompted by an
incident in which the actuator rib fitting of the MLG door on a Model
727 series airplane fractured and, consequently, the left MLG of the
airplane failed to extend for landing. The requirements of that AD are
intended to prevent damage to the airplane caused by a failure of the
landing gear to extend due to a fractured rib fitting.
Description of Previous Proposal
The previously issued NPRM proposed to supersede AD 90-02-19 to:
1. expand the area of the inspections to require either a high
frequency eddy current or dye penetrant inspection to detect cracking
in an expanded area of the actuator rib fitting of the MLG, and various
follow-on actions;
2. in cases where no cracking was found, first require modification
of the rib fitting assembly and, after modification, either repetitive
high frequency eddy current or dye penetrant inspections; and
3. in cases where cracking was found, require the replacement of
the currently installed aluminum rib fitting with a new steel rib
fitting. (This replacement would terminate the repetitive inspections
of the fitting.)
That proposal was prompted by an additional report of an MLG on a
Model 727 series airplane failing to extend for landing, due to a
fractured rib fitting. The broken rib fitting caused the MLG door and
MLG to retract improperly (out of sequence), which led to the MLG
jamming against the MLG door. That airplane had accumulated 34,039
flight hours and 22,777 landings. The fitting on that airplane had been
reworked in accordance with the requirements of AD 90-02-19; no follow-
on inspections of the reworked fitting were required by that AD.
Further, the area of inspection specified by AD 90-02-19 did not
include the area of the fitting in which this cracking was found.
Actions Since Issuance of Previous Proposal
Since issuance of the NPRM, the FAA has received another report of
an operator who experienced a failure of the MLG door actuator rib
fitting. The fitting failed due to a fracture at the transitional
radius. The failure occurred at 1,350 flight cycles after the operator
had inspected a rib fitting that had been modified (reworked) in
accordance with Boeing Service Bulletin 727-32-0364, which is required
by AD 90-02-19. Although that AD does not require repetitive
inspections of modified rib fittings, this operator had elected to
inspect them regularly on the airplanes in its fleet. The data from
this latest incident of cracking confirm the FAA's determination that
repetitive inspections of modified rib fittings are warranted, and that
those inspections must be conducted at more frequent intervals than
proposed in the previous NPRM.
Based on this data, the FAA has revised the proposal to require
inspections of rib fittings that previously have been modified in
accordance with Boeing Service Bulletin 727-32-0364 (but not in
accordance with Boeing Service Bulletin 727-32-0383) at intervals of
1,000 flight cycles.
In addition, the FAA has made other changes to this proposal, based
on comments received in response to the NPRM, as well as in response to
the NPRM issued as Docket 95-NM-222-AD (61 FR 14269, April 1, 1996).
These comments and the ensuing changes are discussed below.
Request To Combine Proposals
Several commenters request that the FAA combine the proposed AD
with another proposal that was issued as Docket 95-NM-222-AD. That
action proposed to revise AD 93-01-14, amendment 39-8468 (58 FR 5574,
January 22, 1993), to continue to require:
1. repetitive inspections to detect loose attach fitting bolts of
door actuator of the MLG;
2. repetitive inspections to determine whether the serrations of
the attach fitting of the door actuator of the MLG are fully mated; and
3. various follow-on corrective actions.
It also proposed to provide operators the option of terminating all
of the inspections required by AD 93-01-14 either by replacing the
currently installed aluminum rib fitting with a new steel rib fitting,
or by modifying the rib fitting assembly in accordance with Boeing
Alert Service Bulletin 727-32A0399 and accomplishing follow-on actions.
Such replacement or modification would also terminate the inspections
currently required by AD 90-02-19.
Since the actions of both of these proposals are so closely
related, the commenters suggest that they be combined into one single
AD action. The commenters maintain that doing so would create less
confusion for operators.
The FAA concurs, and has revised this proposal (Docket 95-NM-223-
AD) to include all of the requirements related to inspections of the
MLG actuator rib fitting assembly. By separate rulemaking, the FAA will
withdraw Docket 95-NM-222-AD, since its proposed actions are now
covered by this new supplemental NPRM.
Requests To Revise Initial Inspection Intervals
Several commenters request that the FAA revise the proposed initial
interval for the inspection to detect cracking of the actuator rib
fitting. The proposal would have required that the inspection be
conducted at the later of the following:
--prior to the accumulation of 20,000 total flight cycles; or
--prior to the accumulation of 1,000 flight cycles after the effective
date of the AD or within 2,500 flight cycles after the immediately
preceding inspection performed in accordance with AD 90-02-19,
whichever is earlier.
One commenter requests that the inspection be required at intervals
of 2,500 flight cycles after the effective date, since this would allow
the inspection to be accomplished during this commenter's regularly
scheduled ``C'' check. Another commenter states that accomplishing the
visual inspection at 1,000 flight cycles, and the high frequency eddy
current or dye penetrant inspection at 2,500 flight cycles, would
better suit normal maintenance schedules and still provide an
acceptable level of safety. Another commenter states that the initial
inspection interval is too restrictive and does not give credit to
operators who already have been performing repetitive inspections at
2,500-flight cycle intervals or if the last inspection was performed
more than 1,500 flight cycles previously. Another commenter states that
most operators have already accomplished at least a visual inspection
of the fitting as a result of the issuance of Boeing All Base Telex
[[Page 51252]]
M-7272-94-2747, dated May 19, 1994, and should receive credit for doing
it.
The FAA agrees that the initial inspection interval may be changed
somewhat, although not necessarily for the reasons suggested by the
commenters. As explained previously in this preamble, because new
cracking has been found on modified rib fittings, the FAA finds that
airplanes on which the rib fittings have been previously modified must
continue to be inspected. The FAA has considered this cracking data and
the various configurations of airplanes (those having some modified
fittings, and those having no modified fittings) that will be affected
by this proposal, and has revised the proposed schedule for inspections
as follows:
1. Airplanes equipped with actuator rib fittings that have been
modified in accordance with Boeing Service Bulletin 727-32-0364, but
not with Boeing Service Bulletin 727-32-0383, must be inspected within
1,000 flight cycles.
2. Airplanes equipped with rib fittings that have been modified in
accordance with both Boeing Service Bulletin 727-32-0364 and Boeing
Service Bulletin 727-32-0383, must be inspected at the later of (a)
1,000 flight cycles from the effective date of the AD or (b) 1,500
flight cycles after the immediately preceding inspection performed in
accordance with AD 90-02-19, or within 1,500 flight cycles after
accomplishment of the ``terminating action'' specified in AD 93-01-14,
whichever is earlier.
3. Airplanes equipped with rib fittings that have been modified in
accordance with Boeing Alert Service Bulletin 727-32A0399 must be
inspected within 7,500 flight cycles after modification (and thereafter
at intervals not to exceed 2,500 flight cycles).
The FAA considers these inspection times to be warranted, based on
the data available, and they should fit into normally scheduled
maintenance intervals for most affected operators.
Request To Extend Compliance Time for Modification
One commenter requests that the proposed rule be revised to provide
for a 3-year compliance time for modification of the rib fitting
assemblies (in accordance with Boeing Alert Service Bulletin 727-
32A0399) if no cracking is detected. This commenter points out that the
repetitive inspections have been shown to be safe, and that the FAA's
proposal to modify the fittings at 1,000 flight cycles after the
effective date of the AD is not justified. The commenter contends that
adoption of the proposed compliance time would require that this
commenter special schedule its fleet for this modification, at
considerable expense over what was estimated by the FAA in it's cost
impact information. As an alternative to modification, this commenter
suggests that operators be allowed to conduct repetitive visual
inspections and high frequency eddy current/dye penetrant inspections
until the fittings are replaced with steel fittings.
The FAA partially concurs with the commenters request. Upon
reconsideration, the FAA agrees that modification within 1,000 flight
cycles may be too restrictive. However, since fatigue fractures such as
those experienced on the rib attach fitting are cycle-dependent, not
time dependent, a calendar time of ``3 years'' is not appropriate for
correcting a fatigue-related problem.
In reviewing the available data, the FAA finds that repetitive
inspections alone will not ensure an acceptable level of safety. The
data also show that the following items are critical in ensuring a safe
actuator rib fitting:
1. proper bolt torque;
2. proper door rigging; and
3. removal of poor fatigue details.
In light of this, the FAA has determined that the modification
interval can be increased, provided that inspections are conducted more
frequently, the door is properly rigged, and the bolts are properly
torqued. The proposed rule has been revised to require these
inspections of bolt torque and door rigging, and to allow more time for
modification of those rib fittings on which other modifications have
been accomplished previously in accordance with Boeing Service Bulletin
727-32-0364 and Boeing Service Bulletin 727-32-0383.
Request To Allow Unmodified Fittings as Replacement Parts
Several commenters request that the proposal be revised to allow
operators to install unmodified fittings as replacement parts. The
commenters point out that the proposed rule would require that all
replacement parts be steel fittings. However, the commenters fear that
there may be a parts availability problem in trying to meet this
requirement.
The FAA concurs partially. The latest incident of cracking,
described previously, indicates that inspections alone are not reliable
in preventing fractures in the aluminum actuator rib fittings. However,
FAA finds that it is acceptable to use an aluminum fitting as a
replacement part, provided that:
1. It is has been inspected in accordance with Figure 2 of Boeing
Alert Service Bulletin 727-32A0399;
2. It has been reworked in accordance with Figure 3 of Boeing Alert
Service Bulletin 727-32A0399 and in accordance with Boeing Service
Bulletin 727-32-0364;
3. After rework, it is installed in accordance with Figure 4 of
Boeing Alert Service Bulletin 727-32A0399; and
4. After installation, it is repetitively inspected until replaced
with a steel fitting.
Paragraph (d) of this supplemental NPRM specifies this.
Request To Make Service Information References More Specific
One commenter requests that all of the references in the proposal
to Boeing service bulletins be revised to make them more specific. The
commenter suggests that these references cite the specific figure in
the service bulletins where procedural instructions are found. The
commenter states that this will provide more clarity to the
requirements and minimize the chances for errors.
While the FAA concurs that additional specificity is necessary, it
does not agree that citing only the ``figure'' in the service bulletin
is adequate in all cases. A reference to only the figure could
inadvertently omit important compliance instructions that are necessary
to accomplish the task. For actions in accordance with Boeing Alert
Service Bulletin 727-32A0399, the FAA finds that it is more appropriate
to reference ``Part I,'' ``Part II,'' or ``Part III'' of the
Accomplishment Instructions, rather than to reference only the figures
related to those Parts; by doing this, operators will be required to
consider all steps of the pertinent actions when accomplishing the
task, and not just the steps listed in the figures. The FAA has revised
the final rule to include references to these ``Part'' numbers where
appropriate.
Request To Provide an Option to Certain Steps in Modification
Requirement
One commenter requests that the proposed rule provide an option to
the specific modification procedures called out in Step 1 of Figure 3
of Boeing Alert Service Bulletin 727-32A0399. That step requires the
machining of a 0.42-inch, plus/minus 0.03-inch, transition radius.
According to the service bulletin, this modification is to be
accomplished with the doors still installed on the airplane. However,
the commenter states that several machinists have expressed concern
over their ability to machine such a tight tolerance radius, under
these
[[Page 51253]]
conditions, on a rib fitting that has already been modified by AD 90-
02-19. The commenter has examined the costs of removing the door and
sending it to a machine shop for rework, but found this process to be
cost-prohibitive. Based on this experience, the commenter requests that
the proposal allow operators, in lieu of the specific instructions in
Step 1 of Figure 3, the option of blending out the existing machine
cuts using a .38-inch minimum transition radius to create a smooth
transition between the adjacent surfaces.
The FAA concurs that an option to the procedures specified in the
service bulletin should be provided. This supplemental NPRM would allow
operators to machine a .39 inch minimum transitional radius. A minimum
radius of .39 inch will be used since it is the minimum dimension now
allowed.
Request To Allow Reinstallation of Attaching Hardware
One commenter requests that the proposal be revised to allow
operators to inspect and reinstall serviceable attaching hardware
(i.e., nuts, bolts, and washers) after modifying the rib fitting. This
commenter states that it routinely disassembles the rib fitting during
a regularly scheduled ``C'' check and heavy maintenance visit, and
replaces any corroded hardware found during this process.
The FAA does not consider that any change to the proposal is
necessary based on this commenter's request. The proposed rule does not
mandate the use of new attaching hardware every time the rib fitting is
disassembled; it only requires the use of the attaching hardware that
is included as part of the modification described in Boeing Alert
Service Bulletin 727-32A0399. In addition, that service bulletin
specifies that fasteners may be substituted in accordance with Chapter
51 of the 727 Structural Repair Manual.
Conclusion
Since the change described above expand the scope of the originally
proposed rule, the FAA has determined that it is necessary to reopen
the comment period to provide additional opportunity for public
comment.
Cost Impact
There are approximately 1,631 Boeing Model 727 series airplanes of
the affected design in the worldwide fleet. The FAA estimates that
1,166 airplanes of U.S. registry would be affected by this proposed AD.
The inspections proposed in this AD action would take approximately
10 work hours per airplane to accomplish, 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 is estimated to be $699,600, or
$600 per airplane, per inspection.
The modification proposed in this AD action would take
approximately 6 work hours per airplane to accomplish, at an average
labor rate of $60 per work hour. The cost of required parts would be
negligible. Based on these figures, the cost impact of the proposed
modification on U.S. operators is estimated to be $376,560, or $360 per
airplane.
These cost impact figures 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 proposed terminating
action (installation of steel fittings), it would take approximately 4
work hours per airplane, at an average labor rate of $60 per work hour.
Required parts would cost approximately $428 per airplane. Based on
these figures, the cost impact of this proposed optional terminating
action on U.S. operators is estimated to be $668 per airplane.
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.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing amendment 39-6433 (55 FR
601, January 8, 1990); and by removing amendment 39-8368 (58 FR 5574,
January 22, 1993); and by adding a new airworthiness directive (AD), to
read as follows:
Boeing: Docket 95-NM-223-AD. Supersedes AD 90-02-19, amendment 39-
6433; and supersedes AD 93-01-14, amendment 39-8368.
Applicability: All Model 727 series 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 (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 failure of the main landing gear (MLG) to extend for
landing and subsequent damage to the airplane, accomplish the
following:
(a) For airplanes equipped with rib fittings that have been
modified (reworked) in accordance with Boeing Service Bulletin 727-
32-0364, dated December 15, 1988, or Revision 1, dated October 19,
1989; but have not been modified in accordance with Figure 2 of
Boeing Service Bulletin 727-32-0383, Revision 1, dated January 30,
1992: Accomplish the following:
(1) Prior to the accumulation of 1,000 flight cycles after the
effective date of this AD, accomplish the actions specified in both
paragraphs (a)(1)(i) and (a)(1)(ii):
(i) Perform either a high frequency eddy current or dye
penetrant inspection to detect cracking of the actuator rib fitting
of the
[[Page 51254]]
MLG, in accordance with Part I of the Accomplishment Instructions of
Boeing Alert Service Bulletin 727-32A0399, dated July 13, 1995. And
(ii) Inspect the actuator rib fitting of the MLG to ensure that
serrations are fully mated, and to detect loose bolts, in accordance
with Figure 1 of Boeing Service Bulletin 727-32-0383, Revision 1,
dated January 30, 1992.
(2) If the inspections required by paragraph (a)(1) of this AD
reveal no cracking or loose bolts, and reveal that the serrations
are fully mated, accomplish the actions specified in paragraphs
(a)(2)(i), (a)(2)(ii), and (a)(2)(iii) of this AD:
(i) Prior to further flight, re-rig the door in accordance with
the maintenance manual procedures referenced in Boeing Alert Service
Bulletin 727-32A0399, dated July 13, 1995, to ensure proper door
rigging. And
(ii) Thereafter, repeat the inspections required by paragraph
(a)(1) of this AD at intervals not to exceed 1,000 flight cycles
until the modification required by paragraph (a)(2)(iii) of this AD
is accomplished. And
(iii) Prior to the accumulation of 3,000 flight cycles after the
effective date of this AD, modify the actuator rib fitting in
accordance with Part II of the Accomplishment Instructions of Boeing
Alert Service Bulletin 727-32A0399, dated July 13, 1995. As an
option to the action specified in Step 1 of Figure 3 of that alert
service bulletin, operators may layout a .39-inch minimum radius.
(3) If the inspections required by paragraph (a)(1) of this AD
reveal no cracking, but do reveal loose bolts or serrations that are
not fully mated, prior to further flight accomplish either paragraph
(a)(3)(i) or (a)(3)(ii) of this AD:
(i) Modify the actuator rib fitting in accordance with Part II
of the Accomplishment Instructions of Boeing Alert Service Bulletin
727-32A0399, dated July 13, 1995. As an option to the action
specified in Step 1 of Figure 3 of that alert service bulletin,
operators may layout a .39-inch minimum radius. Or
(ii) Replace the currently-installed aluminum rib fitting with a
new steel rib fitting, in accordance with Part III of the
Accomplishment Instructions of Boeing Alert Service Bulletin 727-
32A0399, dated July 13, 1995. After this replacement, no further
action is required by this AD for that rib fitting.
(b) For airplanes equipped with rib fittings that have been
modified in accordance with Boeing Service Bulletin 727-32-0364,
dated December 15, 1988, or Revision 1, dated October 19, 1989; and
have been modified in accordance with Figure 2 of Boeing Service
Bulletin 727-32-0383, Revision 1, dated January 30, 1992: Accomplish
the following:
(1) Perform either a high frequency eddy current or dye
penetrant inspection to detect cracking of the actuator rib fitting
of the MLG, in accordance with Part I of the Accomplishment
Instructions of Boeing Alert Service Bulletin 727-32A0399, dated
July 13, 1995, at the later of the times specified in either
paragraph (b)(1)(i) or (b)(1)(ii) of this AD.
(i) Prior to the accumulation of 1,000 flight cycles after the
effective date of the AD; or
(ii) Within 1,500 flight cycles after the immediately preceding
inspection performed in accordance with AD 90-02-19, or within 1,500
flight cycles after accomplishing the terminating action in
accordance with AD 93-01-14, whichever is earlier.
(2) If no cracking is detected during the inspection required by
paragraph (b)(1) of this AD, accomplish the actions specified in
paragraphs (b)(2)(i), (b)(2)(ii), and (b)(2)(iii) of this AD:
(i) Prior to further flight, re-rig the door in accordance with
the maintenance manual procedures referenced in Boeing Alert Service
Bulletin 727-32A0399, dated July 13, 1995, to ensure proper door
rigging. And
(ii) Thereafter, repeat the inspection required by paragraph
(b)(1) at intervals not to exceed 2,500 flight cycles until the
modification required by paragraph (b)(2)(iii) of this AD is
accomplished. And
(iii) Prior to the accumulation of 6,000 flight cycles after the
effective date of this AD, modify the actuator rib fitting in
accordance with Part II of the Accomplishment Instructions of Boeing
Alert Service Bulletin 727-32A0399, dated July 13, 1995. A s an
option to the action specified in Step 1 of Figure 3 of that alert
service bulletin, operators may layout a .39-inch minimum radius.
(c) For airplanes equipped with rib fittings that have not been
modified in accordance with Boeing Service Bulletin 727-32-0364,
dated December 15, 1988, or Revision 1, dated October 19, 1989:
Accomplish the following:
(1) Prior to the accumulation of 1,000 flight cycles after the
effective date of this AD, accomplish the actions specified in both
paragraphs (c)(1)(i) and (c)(1)(ii) of this AD:
(i) Perform either a high frequency eddy current or dye
penetrant inspection to detect cracking of the actuator rib fitting
of the MLG, in accordance with Part I of the Accomplishment
Instructions of Boeing Alert Service Bulletin 727-32A0399, dated
July 13, 1995. And
(ii) Inspect the actuator rib fitting of the MLG to ensure that
serrations are fully mated, and to detect loose bolts, in accordance
with Figure 1 of Boeing Service Bulletin 727-32-0383, Revision 1,
dated January 30, 1992.
(2) If the inspections required by paragraph (c)(1) of this AD
reveal no cracking or loose bolts, and reveal that the serrations
are fully mated, prior to further flight, accomplish the actions
specified in either paragraph (c)(2)(i), (c)(2)(ii), or (c)(2)(iii)
of this AD:
(i) Modify the actuator rib fitting in accordance with Part II
of the Accomplishment Instructions of Boeing Alert Service Bulletin
727-32A0399, dated July 13, 1995; and in accordance with Boeing
Service Bulletin 727-32-0364, dated December 15, 1988, or Revision
1, dated October 19, 1989. As an option to the action specified in
Step 1 of Figure 3 of Boeing Alert Service Bulletin 727-32A0399,
operators may layout a .39-inch minimum radius. Or
(ii) Replace the currently-installed aluminum rib fitting with a
new steel rib fitting, in accordance with Part III of the
Accomplishment Instructions of Boeing Alert Service Bulletin 727-
32A0399, dated July 13, 1995. After this replacement, no further
action is required by this AD for that fitting. Or
(iii) Replace the fitting with a like fitting that has been
inspected in accordance with Part I of the Accomplishment
Instructions of Boeing Alert Service Bulletin 727-32A0399, dated
July 13, 1995; and modified in accordance with Part II of the
Accomplishment Instructions of that service bulletin and in
accordance with Boeing Service Bulletin 727-32-0364, dated December
15, 1988, or Revision 1, dated October 19, 1989.
(d) If any cracking is detected during the inspections required
by paragraphs (a)(1), (b)(1), or (c)(1) of this AD, prior to further
flight, accomplish the actions specified in either paragraph (d)(1)
or (d)(2) of this AD:
(1) Replace the cracked fitting with a like fitting that has
been inspected in accordance with Part I of the Accomplishment
Instructions of Boeing Alert Service Bulletin 727-32A0399, dated
July 13, 1995; and modified in accordance with Part II of the
Accomplishment Instructions of that service bulletin and in
accordance with Boeing Service Bulletin 727-32-0364, dated December
15, 1988, or Revision 1, dated October 19, 1989. As an option to the
action specified in Step 1 of Figure 3 of Boeing Alert Service
Bulletin 727-32A0399, operators may layout a .39-inch minimum
radius. Or
(2) Replace the cracked fitting with a new steel rib fitting in
accordance with Part III of the Accomplishment Instructions of
Boeing Alert Service Bulletin 727-32A0399, dated July 13, 1995. This
replacement constitutes terminating action for the requirements of
that AD for that fitting.
(e) For all airplanes on which modification of the actuator rib
fitting has been accomplished in accordance with Part II of the
Accomplishment Instructions of Boeing Alert Service Bulletin 727-
32A0399, dated July 13, 1995; and Boeing Service Bulletin 727-32-
0364, dated December 15, 1988, or Revision 1, dated October 19,
1989: Within 7,500 flight cycles after accomplishing the
modification, accomplish the following:
(1) Perform either a high frequency eddy current or dye
penetrant inspection to detect cracking of the modified actuator rib
fitting, in accordance with the alert service bulletin.
(2) Repeat the inspection thereafter at intervals not to exceed
2,500 flight cycles until the fitting is replaced with a new steel
rib fitting, in accordance with Part III of the Accomplishment
Instructions of the alert service bulletin. This replacement
constitutes terminating action for the requirements of this AD for
that fitting.
(f) Replacement of aluminum actuator rib fittings with new steel
actuator rib fittings in accordance with Part III of the
Accomplishment Instructions of Boeing Alert Service Bulletin 727-
32A0399, dated July 13, 1995, constitutes terminating action for the
requirements of this AD.
(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 Aircraft Certification
Office (ACO), FAA, Transport Airplane Directorate. Operators shall
submit their requests through an
[[Page 51255]]
appropriate FAA Principal Maintenance Inspector, who may add
comments and then send it to the Manager, Seattle ACO.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
(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 September 24, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-25040 Filed 9-30-96; 8:45 am]
BILLING CODE 4910-13-U