[Federal Register Volume 62, Number 207 (Monday, October 27, 1997)]
[Rules and Regulations]
[Pages 55500-55502]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-28082]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 96-CE-17-AD; Amendment 39-10173; AD 97-22-02]
RIN 2120-AA64
Airworthiness Directives; Pilatus Britten-Norman Ltd. Models BN-
2, BN-2A, BN-2B, and BN-2T Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment adopts a new airworthiness directive (AD) that
applies to Pilatus Britten-Norman Ltd. (PBN) BN-2, BN-2A, BN-2B, and
BN-2T series airplanes. This action requires modifying the upper engine
mounting brackets on the wing front spar as terminating action for the
repetitive inspections that were required in AD 84-23-06. AD 84-23-06
is being revised in a separate action, deleting the Pilatus BN-2, BN-
2A, BN-2B, and BN-2T series airplanes from its applicability. This AD
is prompted by several reports of cracks in the upper engine mounting
brackets and a new terminating action to eliminate the repetitive
inspections for Pilatus BN-2, BN-2A, BN-2B, and BN-2T series airplanes.
The actions specified by this AD are intended to prevent the failure of
the upper engine mounting brackets on the wing mounted engines, which
could possibly cause structural failure of the airplane.
DATES: Effective November 24, 1997.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of November 24, 1997.
ADDRESSES: Service information that applies to this AD may be obtained
from Pilatus Britten-Norman Ltd., Bembridge, Isle of Wight, United
Kingdom PO35 5PR; telephone 44-19-83-872511; facsimile 44-19-83-873246.
This information may also be examined at the Federal Aviation
Administration (FAA), Central Region, Office of the Regional Counsel,
Attention: Rules Docket 96-CE-17-AD, Room 1558, 601 E. 12th Street,
Kansas City, Missouri 64106; or at the Office of the Federal Register,
800 North Capitol Street, NW., suite 700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Mr. S. M. Nagarajan, Project Officer,
Small Airplane Directorate, Aircraft Certification Service, FAA, 1201
Walnut, suite 900, Kansas City, Missouri 64105; telephone (816) 426-
6932; facsimile (816) 426-2169.
SUPPLEMENTARY INFORMATION:
Events Leading to the Issuance of This AD
A proposal to amend part 39 of the Federal Aviation Regulations (14
CFR part 39) to include an AD that would apply to Pilatus BN-2, BN-2A,
BN-2B, and BN-2T series airplanes was published in the Federal Register
on March 10, 1997 (62 FR 10754). The action proposed to require
initially inspecting the upper engine mounting brackets on the wing
mounted engines for:
(1) Cracks at the bolt-holes,
(2) Elongation of the bolt holes,
(3) Fretting within the holes,
(4) Cracks at the rivet holes,
(5) Distortion or delamination of the lugs, and that
(6) The bearings are the correct length and the bolts are not
threadbound.
If there is no evidence of damage or defects similar to any of the
above-mentioned items, the proposed AD would require repetitive
inspections at regular intervals until the accumulation of 2,000 hours
time-in-service after the effective date of the AD, at which time the
AD would require accomplishing Pilatus Modification NB/M/1147.
If any damage or defects are found similar to any of the six items
previously mentioned, this action would require immediately
accomplishing Pilatus Modification NB/M/1147. This modification
consists of replacing damaged brackets, bolts, and bushes with parts of
an improved design. Accomplishing this modification is considered a
terminating action to the repetitive inspections. Accomplishment of the
AD would be in accordance with Pilatus Britten-Norman Service Bulletin
No. BN-2/SB.61, Issue 5, dated December 9, 1981.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. No comments were received on the
proposed rule or the FAA's determination of the cost to the public.
The FAA's Aging Aircraft Policy
The FAA has determined that reliance on critical repetitive
inspections on aging commuter-class airplanes carries an unnecessary
safety risk when a design change exists that could eliminate or, in
certain instances, reduce the number of those critical inspections. In
determining what inspections are critical, the FAA considers (1) the
safety consequences if the known problem is not detected during the
inspection; (2) the probability of the problem not being detected
during the inspection; (3) whether the inspection area is difficult to
access; and (4) the possibility of damage to an adjacent structure as a
result of the problem.
These factors have led the FAA to establish an aging commuter-class
aircraft policy that requires incorporating a known design change when
it could replace a critical repetitive inspection.
For Pilatus BN-2, BN-2A, BN-2B, and BN-2T series airplanes, the
manufacturer has incorporated a design change that would replace
damaged bolts, brackets, and bushes with parts of improved design,
which would
[[Page 55501]]
terminate the repetitive inspections of the upper engine mounting
brackets on the wing mounted engines required by AD 84-23-06. It is AD
84-23-06 that required the repetitive inspections on the Pilatus BN-2,
BN-2A, BN-2B, and BN-2T series airplanes and the Pilatus BN-2A MK. 111
series airplanes. A separate action (Docket 84-CE-18-AD) is being
published concurrently with this AD, and revises AD 84-23-06 so that
the BN-2A MK.111 series airplanes will be the only airplanes to which
AD 84-23-06 applies.
Based on its aging commuter-class aircraft policy and after
reviewing all available information, the FAA has determined that AD
action should be taken to modify the upper engine wing mounting
brackets of the affected airplanes to eliminate the repetitive short-
interval inspections, and to prevent failure of the upper engine wing
mounting brackets on wing mounted engines, which could possibly cause
structural failure of the airplane.
The FAA's Determination
After careful review of all available information related to the
subject presented above, the FAA has determined that air safety and the
public interest require the adoption of the rule as proposed except for
minor editorial corrections. The FAA has determined that these minor
corrections will not change the meaning of the AD and will not add any
additional burden upon the public than was already proposed.
Cost Impact
The FAA estimates that 112 airplanes in the U.S. registry will be
affected by the AD, that it will take approximately 37 workhours per
airplane to accomplish the initial inspection and modification, and
that the average labor rate is approximately $60 an hour. Parts cost
approximately $800 per airplane to accomplish the modification. Based
on these figures, the total cost impact of the AD on U.S. operators is
estimated to be $338,240 or $3,020 per airplane. This figure is based
on the initial inspection and modification only. It does not take into
account the cost for the repetitive inspections that may be incurred
over the life of the airplane until the modification is accomplished.
The FAA has no way of determining how many owners/operators have
accomplished the proposed action and, therefore assumes that none of
the owners/operators of the affected airplanes have accomplished the
proposed action.
The AD Action's Impact Utilizing the FAA's Aging Commuter Class
Aircraft Policy
The intent of the FAA's aging commuter airplane program is to
ensure safe operation of commuter-class airplanes that are in
commercial service without adversely impacting private operators. Of
the approximately 112 airplanes in the U.S. registry that will be
affected by this AD, the FAA has determined that approximately 18
percent are operated in scheduled passenger service by 11 different
operators. A significant number of the remaining 82 percent are
operated in other forms of air transportation such as air cargo and air
taxi.
This AD allows 2,000 hours time-in-service (TIS) after the
effective date of the AD before mandatory accomplishment of the design
modification. The average utilization of the fleet for those airplanes
in commercial commuter service is approximately 25 to 50 hours TIS per
week. Based on these figures, operators of commuter-class airplanes
involved in commercial operation will have to accomplish the
modification within 10 to 20 calendar months after the effective date
of the AD. For private owners, who typically operate between 100 to 200
hours TIS per year, this will allow 5 to 10 years before the
modification will be mandatory.
Regulatory Impact
The regulations adopted herein will not have substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this action (1) is
not a ``significant regulatory action'' under Executive Order 12866;
(2) is not a ``significant rule'' under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979); and (3) will not have a
significant economic impact, positive or negative, on a substantial
number of small entities under the criteria of the Regulatory
Flexibility Act. A copy of the final 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, Incorporation by
reference, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration amends part 39 of
the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive
(AD) to read as follows:
97-22-02 Pilatus Britten-Norman LTD.: Amendment 39-10173; Docket
No. 96-CE-17-AD.
Applicability: Models BN-2 (serial numbers 1 through 2033), BN-
2A and BN-2B (serial numbers 1 through 2116), and BN-2T (serial
numbers 419, and 2030 through 2033) 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 within the next 500 hours time-in-service
(TIS) after the last inspection required by AD 84-23-06, or within
the next 100 hours TIS after the effective date of this AD,
whichever occurs later, unless already accomplished, and thereafter
as indicated in the body of this AD.
To prevent failure of the upper mounting brackets on both wing
mounted engines, which could cause structural failure of the
airplane, accomplish the following:
(a) Inspect the upper mounting brackets, bolts, and bushes on
both wing mounted engines in accordance with the ``ACTION-
Inspection'' section in Pilatus Britten-Norman (Pilatus) Service
Bulletin (SB) No. BN-2/SB.61, Issue 5, dated December 9, 1981, for:
(1) Cracks at the bolt holes,
(2) Elongation of the bolt holes,
(3) Fretting within the bolt holes,
(4) Cracks at the rivet holes,
(5) Distortion or delamination of the lugs, and
[[Page 55502]]
(6) Incorrect bearing length and threadbound bolts, b) If the
inspection reveals any evidence of damage or defects similar to the
items in paragraphs (a)(1) through (a)(6), prior to further flight,
accomplish Pilatus Modification NB/M/1147 by replacing the brackets,
bushes, and bolts with brackets, bushes, and bolts of improved
design in accordance with paragraphs 1, 2, 3, and 5 of the
``ACTION--Rectification/Modification'' section in Pilatus SB No. BN-
2/SB.61, Issue 5, dated December 9, 1981.
(c) If damage or defects are found on just one of the two
brackets on each engine, then both brackets must be replaced, prior
to further flight, in accordance with paragraph 1 of the ``ACTION--
Rectification/Modification'' section in Pilatus SB No. BN-2/SB.61,
Issue 5, dated December 9, 1981.
(d) If no damage or defects are found similar to the items in
paragraphs (a)(1) through (a)(6) of this AD, continue to inspect at
intervals not to exceed 500 hours TIS, until the accumulation of
2,000 hours TIS after the effective date of this AD, at which time
Modification NB/M/1147 must be accomplished on both upper mounting
brackets on both engines in accordance with paragraphs 1, 2, 3, and
5 of the ``ACTION--Rectification/Modification'' section of Pilatus
SB No. BN-2/SB.61, Issue 5, dated December 9, 1981.
(e) Accomplishing Modification NB/M/1147 in the ``ACTION--
Rectification/Modification'' section of Pilatus SB No. BN-2/SB.61,
Issue 5, dated December 9, 1981, is considered terminating action to
the repetitive inspections required in paragraph (d) of this AD.
(f) 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.
(g) An alternative method of compliance or adjustment of the
initial or repetitive compliance times that provides an equivalent
level of safety may be approved by the Manager, Small Airplane
Directorate, Aircraft Certification Service, FAA, 1201 Walnut, suite
900, Kansas City, Missouri 64105. The request shall be forwarded
through an appropriate FAA Maintenance Inspector, who may add
comments and then send it to the Manager, Small Airplane
Directorate.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from Small Airplane Directorate.
(h) The inspections and modifications required by this AD shall
be done in accordance with Pilatus Britten-Norman Ltd. Service
Bulletin No. BN-2/SB.61, Issue 5, dated December 9, 1981. This
incorporation by reference was approved by the Director of the
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part
51. Copies may be obtained from Pilatus Britten-Norman Ltd.,
Bembridge, Isle of Wight, United Kingdom PO35 5PR. Copies may be
inspected at the FAA, Central Region, Office of the Regional
Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at
the Office of the Federal Register, 800 North Capitol Street, NW.,
suite 700, Washington, DC.
(i) This amendment (39-10173) becomes effective on November 24,
1997.
Issued in Kansas City, Missouri, on October 16, 1997.
Mary Ellen A. Schutt,
Acting Manager, Small Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-28082 Filed 10-24-97; 8:45 am]
BILLING CODE 4910-13-U
