[Federal Register Volume 62, Number 46 (Monday, March 10, 1997)]
[Proposed Rules]
[Pages 10754-10756]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-5846]


========================================================================
Proposed Rules
                                                Federal Register
________________________________________________________________________

This section of the FEDERAL REGISTER contains notices to the public of 
the proposed issuance of rules and regulations. The purpose of these 
notices is to give interested persons an opportunity to participate in 
the rule making prior to the adoption of the final rules.

========================================================================


Federal Register / Vol. 62, No. 46 / Monday, March 10, 1997 / 
Proposed Rules

[[Page 10754]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-CE-17-AD]
RIN 2120-AA64


Airworthiness Directives; Pilatus Britten-Norman Ltd. BN-2, BN-
2A, BN-2B, and BN-2T Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: This document proposes to adopt a new airworthiness directive 
(AD) that would apply to Pilatus Britten-Norman Ltd. (Pilatus) BN-2, 
BN-2A, BN-2B, and BN-2T series airplanes. The proposed action would 
require 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, which is the subject of a proposal to 
eliminate the Pilatus BN-2, BN-2A, BN-2B, and BN-2T series airplanes 
from its applicability in a separate action. The proposed action 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 the proposed AD are intended to prevent the 
failure of the engine mounting brackets on the wing mounted engines 
which could possibly cause structural failure of the airplane.

DATES: Comments must be received on or before May 12, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Central Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 96-CE-17-AD, Room 1558, 601 E. 
12th Street, Kansas City, Missouri 64106. Comments may be inspected at 
this location between 8 a.m. and 4 p.m., Monday through Friday, 
holidays excepted.
    Service information that applies to the proposed AD may be obtained 
from Pilatus Britten-Norman Ltd., Bembridge, Isle of Wight, United 
Kingdom PO35 5PR; telephone 44-1983 872511; facsimile 44-1983 873246. 
This information also may be examined at the Rules Docket at the 
address above.

FOR FURTHER INFORMATION CONTACT: Tom Rodriguez, Project Engineer, FAA, 
Brussels Aircraft Certification Division, Europe, Africa, and Middle 
East Office, c/o American Embassy, B-1000 Brussels, Belgium; telephone 
(322) 513.3830, ext. 2716; facsimile (322) 230.6899; or 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:

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 should 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 that summarizes 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 No. 96-CE-17-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, Central Region, Office of the Assistant Chief Counsel, 
Attention: Rules Docket No. 96-CE-17-AD, Room 1558, 601 E. 12th Street, 
Kansas City, Missouri 64106.

Events Leading to the Proposed Action

    The Civil Airworthiness Authority (CAA), which is the airworthiness 
authority for the United Kingdom (UK), notified the FAA that an unsafe 
condition may exist on Pilatus BN-2, BN-2A, BN-2B, and BN-2T series 
airplanes. The UK CAA reports cracking in the upper engine mounting 
brackets on the wing mounted engines attached to the wing front spar. 
This condition, if not detected and corrected, could result in failure 
of the engine mounting brackets of the wing mounted engines and 
possible structural failure and loss of control of the airplane.
    The Pilatus BN-2, BN-2A, BN-2B, and BN-2T series airplanes are 
included in the applicability section of AD 84-23-06. A proposal to 
remove these airplanes from the applicability of AD 84-23-06 is being 
issued in a separate revised Notice of Proposed Rulemaking. The 
repetitive inspections that have been required by AD 84-23-06 would be 
terminated with a modifying action that is only applicable to the BN-2, 
BN-2A, BN-2B, and BN-2T series airplanes in this proposed action.

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

[[Page 10755]]

aircraft policy that requires incorporating a known design change when 
it could replace a critical repetitive inspection.
    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.

Related Service Information

    Pilatus issued Service Bulletin No. BN-2/SB.61, Issue 5, dated 
December 9, 1981, which specifies procedures for modifying the engine 
mounting brackets on the wing mounted engines and terminating the 
repetitive inspection after accomplishing the modification.
    The UK CAA classified these service bulletins as mandatory and has 
issued AD No. 0619 in order to assure the continued airworthiness of 
these airplanes in the United Kingdom.

FAA's Determination

    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 UK CAA has kept the FAA 
informed of the situation described above. The FAA has examined the 
findings of the UK CAA, reviewed all available information including 
the service information referenced above, and determined that AD action 
is necessary for products of this type design that are certificated for 
operation in the United States.
    Since an unsafe condition has been identified that is likely to 
exist or develop in other Pilatus BN-2, BN-2A, BN-2B, and BN-2T series 
airplanes of the same type design registered in the United States, the 
proposed AD would 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, continue to repetitively inspect at regular 
intervals until the accumulation of 2,000 hours time-in-service after 
the effective date of the proposed AD, at which time the proposed 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, prior to further flight, the proposed action 
would require 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 proposed repetitive inspections.

Cost Impact

    The FAA estimates that 112 airplanes in the U.S. registry would be 
affected by the proposed AD, that it would 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 
proposed 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 to 
determine the number of owners/operators that may have already 
accomplished the proposed action.

The Proposed 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 would be 
affected by the proposed 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.
    The proposed AD allows 2,000 hours time-in-service (TIS) after the 
effective date of the proposed 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 would have to accomplish the 
proposed modification within 5 to 10 calendar months after the proposed 
AD would become effective. For private owners, who typically operate 
between 100 to 200 hours TIS per year, this would allow 5 to 10 years 
before the proposed modification would be mandatory.

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 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) 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 has been placed 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.

[[Page 10756]]

Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding a new airworthiness directive 
(AD) to read as follows:

Pilatus Britten-Norman Ltd.: Docket No. 96-CE-17-AD.

    Applicability: Models BN-2 (serial numbers 1 through 2033), BN-
2T (serial numbers 419, and 2030 through 2033), and Models BN-2A and 
BN-2B (serial numbers 1 through 2116), 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 compliance with AD 84-23-06, or within the next 
100 hours TIS after the effective date of this AD, whichever occurs 
later, unless already accomplished.
    To prevent failure of the upper mounting brackets on both wing 
mounted engines which could possibly cause structural failure of the 
airplane, accomplish the following:
    (a) Inspect the upper mounting brackets, bolts, and bushings on 
both wing mounted engines 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
    (6) Correct bearing length and inspect for bolts that are 
threadbound, 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.
    (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 (part number 
(P/N) NB-20-D-7165), bushes (P/N NB-20-A4-7171), 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, Brussels Aircraft 
Certification Division, Europe, Africa, and Middle East Office, c/o 
American Embassy, B-1000 Brussels, Belgium or the Manager, Small 
Airplane Directorate, 1201 Walnut, suite 900, Kansas City, Missouri 
64106. The request shall be forwarded through an appropriate FAA 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Brussels Aircraft Certification Division or the Small 
Airplane Directorate.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Brussels Aircraft Certification Division or the 
Small Airplane Directorate.

    (h) All persons affected by this directive may obtain copies of 
the document referred to herein upon request to Pilatus Britten-
Norman Ltd., Bembridge, Isle of Wight, United Kingdom PO35 5PR; or 
may examine this document at the FAA, central Region, Office of the 
Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City, 
Missouri 64106.

    Issued in Kansas City, Missouri, on February 28, 1997.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 97-5846 Filed 3-7-97; 8:45 am]
BILLING CODE 4910-13-U