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[Federal Register Volume 60, Number 11 (Wednesday, January 18, 1995)]
[Proposed Rules]
[Pages 3581-3583]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-1131]

[[Page 3581]]

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-NM-107-AD]

Airworthiness Directives; British Aerospace Model ATP Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to all British Aerospace Model 
ATP series airplanes, that 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. That 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 actions specified by that AD are 
intended to prevent structural failure of the actuator attachment 
point, which could lead to collapse of the MLG. This action would limit 
the applicability of the 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 
would require that modified boom angles be installed whenever 
replacement is necessary.

DATES: Comments must be received by February 22, 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; fax (206) 227-1320.

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

    -On July 14, 1993, the FAA issued AD 93-14-08, amendment 39-8632 
(58 FR 42194, August 9, 1993), applicable to all British Aerospace 
Model ATP series airplanes, to require inspections to detect cracking 
of the aft end of the wing rib boom angles at the left and right 
engine, and repair or replacement of the wing rib boom angle 
assemblies, if necessary. The initial inspection is required within 400 
hours time-in-service after the effective date of the AD, or within 12 
months since airplane manufacture, whichever is later. If no cracks are 
detected, the inspection is required to be repeated at intervals of 
3,000 landings or 12 months, whichever occurs sooner. If cracks are 
detected, the boom angle(s) must be repaired or replaced; or, if 
cracking is within certain limits, the area may be reinspected for a 
period of time until the boom angle is repaired or replaced.
    -The issuance of AD 93-14-08 was prompted by the detection of 
cracks in the engine outboard rib boom angles at the main landing gear 
(MLG) actuator attachment point. The requirements of that AD are 
intended to prevent structural failure of the actuator attachment 
point, which could lead to collapse of the MLG.
    -Since the issuance of that AD, the Civil Aviation Authority (CAA), 
which is the airworthiness authority for the United Kingdom, has 
advised the FAA that airplanes on which modified engine rib boom angles 
have been installed may be less susceptible to the subject cracking 
problems initially. The modified boom angles are of a configuration 
that has improved resistance to cracking. Therefore, for airplanes on 
which this modification is installed, the CAA advises that the initial 
inspection for cracking may be extended beyond that which is currently 
required.
    -British Aerospace has issued Service Bulletin ATP-57-13, Revision 
5, dated June 3, 1994. This revision is essentially the same as 
Revision 1, which was specified in AD 93-14-08 as the appropriate 
source of service information. Like Revision 1, new Revision 5 
describes procedures for repetitive detailed visual inspection to 
detect cracking of the aft end of the engine outboard rib boom angles 
under the wing rib immediately outboard of the left and right engine; 
and describes procedures for replacement of cracked rib boom angle 
assemblies. Revision 5 differs from Revision 1 in that it recommends 
that the initial inspection of airplanes that are equipped with 
modified engine rib boom angles (Modification 10313A) be postponed 
until the modified boom angles have accumulated 30,000 landings. The 
CAA has classified this service bulletin as mandatory.
    -British Aerospace also has issued Service Bulletin ATP 57-16-
10313A, Revision 1, dated July 2, 1994 (as corrected by Errata No. 2, 
dated August 30, 1994), which describes procedures for installing 
Modification 10313A. This modification entails installation of new 
outboard and inboard rib boom angles on the left wing and right wing 
that are less susceptible to cracking. The CAA classified this service 
bulletin as ``optional.''
    -In light of this, the FAA has determined that AD 93-14-08 must be 
amended to allow airplanes on which Modification 10313A is installed to 
be inspected at a compliance threshold that is extended beyond that 
which is [[Page 3582]] currently required. Additionally, the FAA has 
determined that cracked boom angles must be replaced with modified boom 
angles in order to increase the time-in-service prior to the onset of 
cracking, and to reduce the reliance on repetitive inspections in order 
to assure safety over a long period of time.
    -This airplane model is manufactured in the United Kingdom and is 
type certificated for operation in the United States under the 
provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 
21.29) and the applicable bilateral airworthiness agreement. Pursuant 
to this bilateral airworthiness agreement, the CAA has kept the FAA 
informed of the situation described above. The FAA has examined the 
findings of the CAA, reviewed all available information, and determined 
that AD action is necessary for products of this type design that are 
certificated for operation in the United States.
    -The proposed AD would supersede AD 93-14-08 to continue to require 
repetitive visual inspections to detect cracking of the aft end of the 
wing rib boom angles on the wing rib outboard of the left and right 
engine, and repair or replacement of cracked rib boom angle assemblies. 
This proposal would revise the compliance time for the initial 
inspection of airplanes on which Modification 10313A has been 
accomplished. The inspection actions would be required to be 
accomplished in accordance with Service Bulletin ATP-57-13, Revision 1, 
dated January 15, 1993, or Revision 5, dated June 3, 1994.
    -This proposal would require that any cracked boom angle that is 
replaced, must be replaced with a modified boom angle in accordance 
with British Aerospace Service Bulletin ATP-51-16-10313A, Revision 1, 
dated June 3 1994. Any cracked boom angle that is repaired, must be 
repaired in accordance with a method approved by the FAA.
    -Additionally, this proposal would limit the applicability of the 
rule to only Model ATP airplanes having serial numbers 2002 to 2063, 
inclusive. Airplanes that are produced subsequent to serial number 2063 
will be modified in production to include the equivalent of 
Modification 10313A, and will contain in their Manufacturer's 
Recommended Maintenance Program the inspections and inspection 
intervals that would be required by this AD. The FAA has determined 
that these inspections must be mandated (via this proposed AD) for in-
service airplanes having serial numbers 2002 through 2063 on which 
Modification 10313A has been installed (post-production), since the 
Manufacturer's Recommended Maintenance Program currently applicable to 
these airplanes does not adequately address inspections of the modified 
boom angles.
    -Additionally, this proposed superseding AD has been reformatted to 
simplify and clarify the required actions.
    -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 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 (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. 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 series 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. [[Page 3583]] 
    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, Revision 1, 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 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 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: Repeat 
the detailed visual inspection of the rib boom angle 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 
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 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.
    (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.

    (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 January 11, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-1131 Filed 1-17-95; 8:45 am]
BILLING CODE 4910-13-U
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