[Federal Register Volume 63, Number 110 (Tuesday, June 9, 1998)]
[Proposed Rules]
[Pages 31370-31372]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-15203]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-CE-111-AD]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to adopt a new airworthiness directive 
(AD) that would apply to certain Pilatus Britten-Norman Ltd. (PBN) BN-
2, BN-2A, BN-2B, and BN-2A MK.III series airplanes that are equipped 
with a PBN Modification NB/M/256, 50A generator system. The proposed 
action would require inspecting the airplanes that are equipped with a 
50A generator system for a 70A generator. If a 70A generator is 
installed, the proposed action would require replacing the 70A 
generator with a 50A generator, or (for the BN-2, BN-2A, and BN-2B 
series only) upgrading the airplane generator system to a 70A system to 
match the 70A generator. The proposed AD is the result of mandatory 
continuing airworthiness information (MCAI) issued by the airworthiness 
authority for the United Kingdom. The actions specified by the proposed 
AD are intended to prevent damage to the components of the electrical 
system, which could result in electrical system failure during critical 
phases of flight.

DATES: Comments must be received on or before July 17, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Central Region, Office of the Regional Counsel, 
Attention: Rules Docket No. 97-CE-111-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. This information also may be examined at the Rules 
Docket at the address above.

FOR FURTHER INFORMATION CONTACT: Mr. Roger Chudy, Project Officer, FAA, 
Small Airplane Directorate, 1201 Walnut, suite 900, Kansas City, 
Missouri, 64106; 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. 97-CE-111-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 Regional Counsel, Attention: 
Rules Docket No. 97-CE-111-AD, Room 1558, 601 E. 12th Street, Kansas 
City, Missouri 64106.

Discussion

    The Civil Airworthiness Authority (CAA), which is the airworthiness 
authority for the United Kingdom, notified the FAA that an unsafe 
condition may exist on certain PBN BN-2, BN-2A, BN-2B, and BN-2A MK.III 
series airplanes. The CAA reports that some operators have had 70A 
generators installed on 50A systems, which may damage the electrical 
system's components. The 50A generator system, which is known as PBN 
Modification NB/M/256, is not designed to work with a higher ampere 
generator.
    These conditions, if not corrected, could result in damage to the 
electrical systems with consequent failure during critical phases of 
flight.

Relevant Service Information

    PBN has issued Service Bulletin No. BN-2/SB.229, dated October 17, 
1996, which specifies procedures for inspecting for a 70A generator on 
PBN BN-2, BN-2A, BN-2B, and BN-2A MK.III series airplanes that are 
equipped with PBN Modification NB/M/256 (a 50A generator system). If a 
70A generator is installed, the service information specifies 
procedures for replacing the 70A generator with a 50A generator, or 
(for the BN-2, BN-2A, and BN-2B series only) installing PBN 
Modification NB/M/1148, which incorporates a 70A generator system.
    The CAA classified this service bulletin as mandatory and issued 
British

[[Page 31371]]

AD 007-10-96, not dated, in order to assure the continued airworthiness 
of these airplanes in United Kingdom.

The 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 CAA has kept the FAA 
informed of the situation described above.
    The FAA has examined the findings of the 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.

Explanation of the Provisions of the Proposed AD

    Since an unsafe condition has been identified that is likely to 
exist or develop in other PBN BN-2, BN-2A, BN-2B, and BN-2A MK.III 
series airplanes of the same type design registered in the United 
States, the FAA is proposing AD action. The proposed AD would require:
    <bullet> Inspecting the airplane for a 70A generator installed on a 
50A generator system;
    <bullet> For PBN BN-2A MK.III series airplanes, if a 70A generator 
is installed on a 50A generator system, the proposed AD would require 
replacing the 70A generator with a 50A generator;
    <bullet> For the BN-2, BN-2A, and BN-2B series airplanes, the 
proposed AD would require either replacing the 70A generator with a 50A 
generator; or upgrading the 50A generator system to a 70A generator 
system by installing PBN Modification NB/M/1148; and,
    <bullet> If PBN Modification NB/M/1148 is installed, the proposed 
action would require the installation of PBN Modification NB/M/1571 
(which improves the diodes on the 70A generator system).
    Accomplishment of the proposed inspection and installation or 
replacement would be in accordance with PBN Service Bulletin No. BN-2/
SB.229, dated October 17, 1996.

The Proposed Action As It Relates to Current AD's

    The FAA has recently issued AD 98-04-17, Amendment 39-10329 (63 FR 
7696, February 17, 1998), which requires that any PBN BN-2, BN-2A, and 
BN-2B series airplanes that are not equipped with Modification NB/M/
1571, but are equipped with PBN Modification NB/M/1148 (which 
incorporates the 70A generator system) should also be equipped with PBN 
Modification NB/M/1571. AD 98-04-17 does not affect any airplane that 
is equipped with a 50A generator system.
    Since the proposed AD provides an option that would require 
accomplishment of AD 98-04-17, the FAA is including reference of other 
similar AD requirements. Operators of BN-2, BN-2A, and BN-2B series 
airplanes that have 70A generators installed on 50A generator systems, 
and choose the proposed option of upgrading their 50A generator system 
to a 70A generator system, would be subject to the requirements in AD 
98-04-17. This proposed action would concurrently require installing 
higher amperage diodes in the 70A generator.
    Pilatus Britten-Norman has informed the FAA that Modification NB/M/
1148 or Modification NB/M/1571 is not approved for installation on the 
BN-2A MK.III series airplanes.

Cost Impact

    The FAA estimates that 80 airplanes in the U.S. registry would be 
affected by the proposed AD, that it would take approximately 7 
workhours per airplane to accomplish the proposed action, and that the 
average labor rate is approximately $60 an hour. Parts cost 
approximately $500 per airplane. Based on these figures, the total cost 
impact of the proposed AD on U.S. operators is estimated to be $73,600, 
or $920 per airplane.

Proposed Calendar Compliance Time

    The condition addressed by the proposed AD is not caused by actual 
hours time-in-service (TIS) of the aircraft where the affected 
generators are installed. The need for the generator system 
modification or replacement has no correlation to the number of times 
the equipment is utilized or the age of the equipment. For this reason, 
the compliance time of the proposed AD is presented in calendar time 
instead of hours TIS.

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.


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. 97-CE-111-AD.

    Applicability: Models BN-2, BN-2A, BN -2A-2, BN-2A-3, BN-2A-6, 
BN-2A-8, BN-2A-9, BN-2A-20, BN-2A-21, BN-2A-26, BN-2A-27; BN-2B-20, 
BN-2B-21, BN-2B-26, BN-2B-27, BN-2A MK.III, BN-2A MK.111-2, and BN-
2A MK.111-3 airplanes, all serial numbers, certificated in any 
category, that are equipped with PBN Modification NB/M/256, a 50A 
Generator System.

    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 (d) 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

[[Page 31372]]

been eliminated, the request should include specific proposed 
actions to address it.

    Compliance: Required within the next 3 calendar months after the 
effective date of this AD, unless already accomplished.
    To prevent damage to the components of the generator system, 
which could result in generator system failure during critical 
phases of flight, accomplish the following:
    (a) Inspect the generator system for the installation of a 70A 
generator in accordance with the Inspection section of Pilatus 
Britten-Norman (PBN) Service Bulletin (SB) No. BN-2/SB.229, dated 
October 17, 1996.
    (b) If a 70A generator is installed, accomplish the following, 
as applicable:
    (1) For Models BN-2, BN-2A, BN-2A-2, BN-2A-3, BN-2A-6, BN-2A-8, 
BN-2A-9, BN-2A-20, BN-2A-21, BN-2A-26, BN-2A-27, BN-2B-20, BN-2B-21, 
BN-2B-26, and BN-2B-27 airplanes, prior to further flight, either:
    (i) Replace the 70A generator with a 50A generator in accordance 
with the Replacement section of PBN SB No. BN-2/SB.229, dated 
October 17, 1996; or
    (ii) Incorporate PBN Modification NB/M/1148 (a 70A generator 
system) in accordance with the appropriate Pilatus Britten-Norman 
maintenance manual; and, incorporate PBN Modification NB/M/1571 
(installation of improved generator diodes) in accordance with PBN 
SB No. BN-2/228, Issue 2, dated January 17, 1996.

    Note 2: Incorporating PBN Modification NB/M/1571 is the same 
action required by AD 98-04-17, Amendment 39-10329.

    (2) For Models BN-2A MK.III, BN-2A MK.111-2, and BN-2A MK.111-3 
airplanes, prior to further flight, replace the 70A generator with a 
50A generator in accordance with the Replacement section of PBN SB 
No. BN-2/SB.229, dated October 17, 1996.
    (c) 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.
    (d) An alternative method of compliance or adjustment of the 
compliance time that provides an equivalent level of safety may be 
approved by 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, Small Airplane 
Directorate.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Small Airplane Directorate.

    (e) Questions or technical information related to PBN Service 
Bulletin No. BN-2/SB.229, dated October 17, 1996, or Pilatus 
Britten-Norman Service Bulletin No. BN-2/SB.228, dated January 17, 
1996, should be directed to Pilatus Britten-Norman, Ltd., Bembridge, 
Isle of Wight, United Kingdom, PO35 5PR. This service information 
may be examined at the FAA, Central Region, Office of the Regional 
Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106.

    Note 4: The subject of this AD is addressed in British AD 007-
10-96, not dated.

    Issued in Kansas City, Missouri, on June 1, 1998.
Ronald K. Rathgeber,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-15203 Filed 6-8-98; 8:45 am]
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