[Federal Register Volume 60, Number 89 (Tuesday, May 9, 1995)]
[Proposed Rules]
[Pages 24589-24592]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-11356]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 94-NM-107-AD]
Airworthiness Directives; British Aerospace Model ATP 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directive (AD), which would have superseded an existing AD that is
applicable to all British Aerospace Model ATP airplanes. The existing
AD currently requires inspections to detect cracking of the aft end of
the wing rib boom angles on the left and right engine, and repair or
replacement of the wing rib boom angle assemblies, if necessary. The
existing AD was prompted by the detection of cracks in the engine
outboard rib boom angles at the main landing gear (MLG) actuator
attachment point. Its required actions are intended to prevent
structural failure of the actuator attachment point, which could lead
to collapse of the MLG. The previously proposed action would have
limited the applicability of the rule to certain airplanes; revised the
initial inspection threshold for certain modified airplanes; and would
have required that modified boom angles be installed whenever
replacement is necessary. This action revises the proposed rule by
correcting the actions necessary to be accomplished for one specific
type of cracking condition.
DATES: Comments must be received by June 1, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 94-NM-107-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 Jetstream Aircraft, Inc., P.O. Box 16029, Dulles
International Airport, Washington, DC 20041-6029. This information may
be examined at the FAA, Transport Airplane Directorate, 1601 Lind
Avenue, SW., Renton, Washington.
FOR FURTHER INFORMATION CONTACT: William Schroeder, Aerospace Engineer,
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206)
227-2148.
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 94-NM-107-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. 94-NM-107-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
certain British Aerospace Model ATP airplanes, was published as a
notice of proposed rulemaking (NPRM) in the Federal Register on January
18, 1995 (60 FR 3581). That NPRM would have superseded an existing
airworthiness directive (AD) that is applicable to all British
Aerospace Model ATP series airplanes. The existing AD currently
requires inspections to detect cracking of the aft end of the wing rib
boom angles on the left and right engine, and repair or replacement of
the wing rib boom angle assemblies, if necessary. The existing AD was
prompted by the detection of cracks in the engine outboard rib boom
angles at the main landing gear (MLG) actuator attachment point.
The NPRM proposed to limit the applicability of the existing rule
to only a certain number of airplanes; revise the initial inspection
threshold, depending on whether or not certain modifications have been
accomplished on the boom angles; and require that modified boom angles
be installed whenever replacement is necessary.
Since the issuance of that NPRM, the FAA has recognized that one of
the corrective actions proposed for certain cracking indications was
incorrectly stated.
Specifically, proposed paragraph (f) describes the actions that are
to be taken if visual inspections reveal that one rib boom angle is
cracked, and the crack extends beyond bolt hole Y or into bolt hole A.
For conditions of this type of cracking, the NPRM proposed to require
that operators repeat the inspections of the rib boom angle for
additional crack propagation at intervals of 50 hours time-in-service.
If no additional cracking was detected during any of the repetitive
inspections, operators would be required to repair the rib boom angle
or replace the rib boom angle assembly within one month. However, if
additional cracking was detected, operators would be required to repair
or replace prior to further flight.
Those proposed corrective actions were inadvertently iterated in
the NPRM. They are incorrect and, as stated, are unacceptable as
corrective action to address the described cracking conditions.
Additionally, they are at variance with the corrective action
recommended by the manufacturer and described in the service bulletin
referenced in the NPRM as the appropriate source of service information
(i.e., British Aerospace Service Bulletin ATP-57-13, Revision 5, dated
June 3, 1994). Instead, the action that must be taken to address
initial findings of the described cracking is either the repair of the
wing boom angle or replacement of the wing boom angle assembly, prior
to further flight. The FAA has determined that the proposed rule must
be revised to require this specific corrective action.
Since this change expands 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.
The FAA estimates that 10 airplanes of U.S. registry would be
affected by this proposed AD. The inspections that are currently
required by AD 93-14-08 take approximately 2 work hours per airplane to
accomplish. The average labor rate is $60 per work hour. Based on these
figures, the total cost impact of the current inspection requirements
AD on U.S. operators is estimated to be $1,200, or $120 per airplane,
per inspection cycle.
The total cost impact figure discussed above is based on
assumptions that no operator has yet accomplished any of
[[Page 24591]] the proposed requirements of this AD action, and that no
operator would accomplish those actions in the future if this AD were
not adopted. However, since AD 93-14-08 became effective on September
3, 1993, the FAA assumes that at least the initial inspection already
has been performed on several of the affected airplanes. Thus, the
total cost impact of this proposed AD may be reduced by the amount of
the costs associated with those inspections that have already been
accomplished.
Additionally, since this proposed AD would extend the compliance
time for the initial inspection of some airplanes, it has the effect of
reducing the economic burden for operators of those airplanes, since it
would preclude scheduling an airplane for inspections at a time earlier
than is necessary.
Should replacement of the boom angles with modified boom angles be
necessary, it would require approximately 150 work hours to accomplish,
at an average labor charge of $60 per work hour. Required parts would
cost approximately $3,800 per airplane.
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 (44FR 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. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing amendment 39-8632 (58 FR
42194, August 9, 1993), and by adding a new airworthiness directive
(AD), to read as follows:
British Aerospace: Docket 94-NM-107-AD. Supersedes AD 93-14-08,
Amendment 39-8632.
Applicability: Model ATP airplanes; serial numbers 2002 through
2063, inclusive; certificated in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must use the authority
provided in paragraph (j) to request approval from the FAA. This
approval may address either no action, if the current configuration
eliminates the unsafe condition; or different actions necessary to
address the unsafe condition described in this AD. Such a request
should include an assessment of the effect of the changed
configuration on the unsafe condition addressed by this AD. In no
case does the presence of any modification, alteration, or repair
remove any airplane from the applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
To prevent structural failure of the actuator attachment point,
which could lead to collapse of the main landing gear (MLG),
accomplish the following:
(a) Conduct a detailed visual inspection to detect cracking of
the aft end of the engine outboard rib boom angles under the wing
rib outboard of the left and right engine, in accordance with
British Aerospace Service Bulletin ATP-57-13, Revision1, dated
January 15, 1993; or Revision 5, dated June 3, 1994; at the
applicable time indicated below.
(1) For airplanes on which Modification 10313A (reference
British Aerospace Service Bulletin ATP-56-16-1013A, Revision 1,
dated July 2, 1994) has not been accomplished: Conduct the initial
inspection within 400 hours time-in-service after September 8, 1993
(the effective date of AD 93-14-08, amendment 39-8632), or within 12
months since airplane manufacture, whichever occurs later.
(2) For airplanes on which Modification 10313A has been
accomplished (modified inboard and outboard boom angles on both the
left wing and right wing): Conduct the initial inspection prior to
the accumulation of 30,000 landings on the boom angle assembly or
within 12 months after the effective date of this AD, whichever
occurs later.
(b) For the purposes of compliance with this AD, the following
apply:
(1) Repair of cracked rib boom angles shall be accomplished in
accordance with a method approved by the Manager, Standardization
Branch, ANM-113, FAA, Transport Airplane Directorate.
(2) Replacement of cracked rib boom angle assemblies with
modified assemblies shall be accomplished in accordance with British
Aerospace Service Bulletin ATP-57-16-10313A, Revision 1, dated July
2, 1994 (as corrected by Erratum 2, dated August 30, 1994). Prior to
the accumulation of 30,000 landings on the replaced (modified) boom
angle assembly, repeat the inspection in accordance with paragraph
(a) of this AD.
(c) If no crack is detected: Repeat the detailed visual
inspection at intervals not to exceed 3,000 landings or 12 months,
whichever occurs first.
(d) If any crack is detected on only one rib boom angle, and
that crack does not extend beyond bolt hole X: Repeat the detailed
visual inspection of the rib boom angle for additional crack
propagation at intervals not to exceed 300 hours time-in-service.
(1) If no additional crack propagation is detected during any of
the repetitive inspections: Within 6 months after discovery of the
crack, either repair the rib boom angle or replace the rib boom
angle assembly in accordance with paragraph (b) of this AD.
(2) If any of the repetitive inspections reveal that crack
propagation has reached or extends beyond bolt hole Y or into bolt
hole A: Prior to further flight, either repair the rib boom angle or
replace the rib boom assembly in accordance with paragraph (b) of
this AD.
(e) If any crack is detected on only one rib boom angle, and
that crack extends beyond bolt hole X, but not beyond bolt hole Y or
down towards bolt hole A: Repeat the detailed visual inspection of
the rib boom angle for additional crack propagation at intervals not
to exceed 100 hours time-in-service.
(1) If no additional crack propagation is detected during any of
the repetitive inspections: Within 3 months after discovery of the
crack, either repair the rib boom angle or replace the rib boom
angle assembly in accordance paragraph (b) of this AD.
(2) If any of the repetitive inspections reveal that crack
propagation has reached or extends beyond bolt hole Y or into bolt
hole A: Prior to further flight, either repair the rib boom angle or
replace the rib boom angle assembly in accordance with paragraph (b)
of this AD.
(f) If any crack is detected on only one rib boom angle, and
that crack extends beyond bolt hole Y or into bolt hole A: Prior to
further flight, either repair the rib boom angle or replace the rib
boom angle assembly in accordance with paragraph (b) of this AD.
(g) If any crack is detected on both rib boom angles, and cracks
do not extend beyond bolt hole X: Repeat the detailed visual
inspection of the rib boom angles for additional crack propagation
at intervals not to exceed 100 hours time-in-service.
[[Page 24592]]
(1) If no additional crack propagation is detected during any of
the repetitive inspections: Within 3 months after discovery of the
cracks, either repair the rib boom angles or replace the rib boom
angle assembly in accordance with paragraph (b) of this AD.
(2) If any of the repetitive inspections reveal that crack
propagation has reached or extends beyond bolt hole Y or into bolt
hole A: Prior to further flight, either repair the rib boom angles
or replace the rib boom angle assembly in accordance with paragraph
(b) of this AD.
(h) If any crack is detected on both rib boom angles, and cracks
extend beyond bolt hole X, but not beyond bolt hole Y or down
towards bolt hole A: Repeat the detailed visual inspection of the
rib boom angles for additional crack propagation at intervals not to
exceed 50 hours time-in-service.
(1) If no additional crack propagation is detected during any of
the repetitive inspections: Within 1 month after discovery of the
cracks, either repair the rib boom angles or replace the rib boom
angle assembly in accordance with paragraph (b) of this AD.
(2) If any of the repetitive inspections reveal that crack
propagation has reached or extends beyond bolt hole Y or into bolt
hole A: Prior to further flight, either repair the rib boom angles
or replace the rib boom angle assembly in accordance with paragraph
(b) of this AD.
(i) If any crack is detected on both rib boom angles, and cracks
extend beyond bolt hole Y or into bolt hole A: Prior to further
flight, either repair the rib boom angles or replace the rib boom
angle assembly in accordance with paragraph (b) of this AD
(j) 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, Standardization Branch, ANM-113,
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,
Standardization Branch, ANM-113.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Standardization Branch, ANM-113.
Note 3: Alternative methods of compliance previously granted for
amendment 39-8632, AD 93-14-08, continue to be considered as
acceptable alternative methods of compliance with this amendment.
(k) 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 May 3, 1995.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-11356 Filed 5-8-95; 8:45 am]
BILLING CODE 4910-13-U
