[Federal Register Volume 60, Number 190 (Monday, October 2, 1995)]
[Rules and Regulations]
[Pages 51321-51323]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-22589]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-107-AD; Amendment 39-9368; AD 95-19-06]


Airworthiness Directives; Jetstream Model ATP Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes 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 amendment limits the applicability of the rule to only 
a certain number of airplanes; revises the initial inspection 
threshold, depending on whether or not certain modifications have been 
accomplished on the boom angles; and requires that modified boom angles 
be installed whenever replacement is necessary.

DATES: Effective November 1, 1995.
    The incorporation by reference of certain publications, as listed 
in the regulations, is approved by the Director of the Federal Register 
as of November 1, 1995.
    The incorporation by reference of British Aerospace Service 
Bulletin ATP-57-13, Revision 1, dated January 15, 1993 was approved 
previously by the Director of the Federal Register as of September 8, 
1993 (58 FR 42194, August 9, 1993).

ADDRESSES: The service information referenced in this AD 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 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: 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) 227-1149.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by superseding AD 93-14-08, 
amendment 39-8632 (58 FR 42194, August 9, 1993), which is applicable to 
all British Aerospace Model ATP series airplanes, was published as a 
supplemental notice of proposed rulemaking in the Federal Register on 
May 9, 1995 (60 FR 24589). The action proposed to continue to require 
repetitive detailed 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. It also proposed to limit the applicability of the rule, 
revise the initial inspection threshold, and require that modified boom 
angles 

[[Page 51322]]
be installed whenever replacement of the boom angles is necessary.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the single comment received.
    The commenter supports the proposed rule.
    The FAA has revised the final rule to reflect the corporate name 
change of British Aerospace to Jetstream Aircraft Limited.
    After careful review of the available data, including the comment 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the change previously 
described. The FAA has determined that this change will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.
    The FAA estimates that 10 airplanes of U.S. registry will be 
affected by this 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 
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 AD may 
be reduced by the amount of the costs associated with those inspections 
that have already been accomplished.
    Additionally, since this AD will 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 will 
preclude scheduling an airplane for inspection at a time earlier than 
is necessary.
    Should replacement of the boom angles with modified boom angles be 
necessary, it will require approximately 150 work hours to accomplish, 
at an average labor charge of $60 per work hour. Required parts will 
cost approximately $3,800 per airplane.
    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), 40101, 40113, 44701.


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), amendment 39-9368, to read as follows:
95-19-06  Jetstream Aircraft Limited (Formerly British Aerospace 
Commercial Aircraft Limited): Amendment 39-9368. 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) of this AD 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, Revision 1, dated 
January 15, 1993; or Jetstream Service Bulletin ATP-57-13, 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 
Jetstream 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. 

[[Page 51323]]

    (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: 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.

    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.
    (l) The inspections shall be done in accordance with Jetstream 
Service Bulletin ATP-57-13, Revision 5, dated June 3, 1994. Revision 
5 of Jetstream Service Bulletin ATP-57-13 contains the following 
list of effective pages:

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                                Revision                                
          Page No.             level shown       Date shown on page     
                                 on page                                
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1-3, 5......................            5   June 3, 1994.               
4, 6........................            4   May 31, 1994.               
7-12........................            3   Mar. 23, 1994.              
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The replacement shall be done in accordance with British Aerospace 
Service Bulletin ATP-57-13, Revision 1, dated January 15, 1993, or 
Jetstream Service Bulletin ATP-57-16-10313A, Revision 1, dated July 
2, 1994 (as corrected by Erratum 2, dated August 30, 1994). The 
incorporation by reference of British Aerospace Service Bulletin 
ATP-57-13, Revision 1, dated January 15, 1993, was approved 
previously by the Director of the Federal Register in accordance 
with 5 U.S.C. 552(a) and 1 CFR part 51 as of September 8, 1993 (58 
FR 42194, August 9, 1993). The incorporation by reference of the 
remainder of the service documents listed above is 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 Jetstream Aircraft, 
Inc., P.O. Box 16029, Dulles International Airport, Washington, DC 
20041-6029. 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.
    (m) This amendment becomes effective on November 1, 1995.

    Issued in Renton, Washington, on September 6, 1995.
Darrell M. Pederson,
 Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-22589 Filed 9-29-95; 8:45 am]
BILLING CODE 4910-13-U