Airworthiness Directives; Pilatus Britten-Norman BN2A, BN2B, and BN2T Islander Series and BN2A Mk III Trislander Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-CE-10-AD]

Airworthiness Directives; Pilatus Britten-Norman BN2A, BN2B, and

BN2T Islander Series and BN2A Mk III Trislander 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 Pilatus Britten-Norman BN2A, BN2B, and BN2T

Islander and BN2A Mk III Trislander series airplanes that are equipped

with a nose wheel steering disconnect system with either a Modification

NB/M/503 or Modification NB/M/733 nose undercarriage unit. The proposed

action would require repetitively inspecting the nose wheel steering

drive ring for cracks, and replacing any cracked drive ring. A report

of the rudder pedals jamming in the central position during a takeoff

on one of the affected airplanes prompted the proposed action. The

actions specified by the proposed AD are intended to prevent failure of

the nose wheel steering system because of a cracked drive ring, which

could result in the inability to move the rudder pedals.

DATES: Comments must be received on or before December 30, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Central Region, Office of the Assistant Chief

Counsel, Attention: Rules Docket No. 94-CE-10-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. Delano D. Castle, Program Manager, Brussels Aircraft Certification

Office, FAA, Europe, Africa, and Middle East Office, c/o American

Embassy, B-1000 Brussels, Belgium; telephone (322) 513.3830, extension

2716; facsimile (322) 230.6899; or Mr. John P. Dow, Sr., Project

Officer, Small Airplane Directorate, Airplane Certification Service,

FAA, 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. 94-CE-10-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. 94-CE-10-AD, Room 1558, 601 E. 12th Street,

Kansas City, Missouri 64106.

Discussion

The Civil Aviation Authority (CAA), which is the airworthiness

authority for the United Kingdom, recently notified the FAA that an

unsafe condition may exist on Pilatus Britten-Norman BN2A, BN2B, and

BN2T Islander and BN2A Mk III Trislander series airplanes that are

equipped with a nose wheel steering disconnect system with either a

Modification NB/M/503 or Modification NB/M/733 nose undercarriage unit.

The CAA advises that the rudder pedals jammed in the central position

during a takeoff run on a BN2B Islander series airplane. Initial

investigation revealed that the nose wheel steering drive ring had

fractured and the broken portion of the ring became snagged in the cut-

away section of frame 19 where the steering cables pass through. This

caused the inability to move the rudder pedals. Further investigation

showed that the drive ring had cracked from the small radius of the

left front lug across the ring and also through the grease nipple hole

at the rear left side of the ring.

Pilatus Britten-Norman has issued Service Bulletin No. BN-2/SB.214,

Issue 1, dated September 23, 1993, which specifies procedures for

inspecting the nose wheel steering drive ring. In order to assure the

continued airworthiness of these airplanes in the United Kingdom, the

CAA listed the actions specified in this service bulletin in the

Mandatory Aircraft Modifications and Inspections Summary, Issue 8,

dated March 1994, as UK CAA AD 005-09-93.

This airplane model is manufactured in the United Kingdom and is

type certificated for operation in the United States under the

provisions of Sec. 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.

Since an unsafe condition has been identified that is likely to

exist or develop in other Pilatus Britten- Norman BN2A, BN2B, and BN2T

Islander and BN2A Mk III Trislander series airplanes of the same type

design that are equipped with a nose wheel steering disconnect system

with either a Modification NB/M/503 or Modification NB/M/733 nose

undercarriage unit, the proposed AD would require repetitively

inspecting the nose wheel steering drive ring for cracks, and replacing

any cracked drive ring. The proposed inspection would be accomplished

in accordance with Pilatus Britten-Norman Service Bulletin No. BN-2/

SB.214, Issue 1, dated September 23, 1993. The drive ring replacement,

if necessary, would be accomplished in accordance with the applicable

maintenance manual.

The FAA estimates that 15 airplanes in the U.S. registry would be

affected by the proposed AD, that it would take approximately 1

workhour per airplane to accomplish the proposed action, and that the

average labor rate is approximately $55 an hour. Based on these

figures, the total cost impact of the proposed AD on U.S. operators is

estimated to be $825. This figure does not take into account the cost

of repetitive inspections nor the cost of replacing any cracked drive

ring. The FAA has no way of determining how many repetitive inspections

each operator would incur over the lifetime of the airplane or how many

drive rings may be cracked.

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. 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 adding a new AD to read as follows:

Pilatus Britten-Norman: Docket No. 94-CE-10-AD.

Applicability: BN2A, BN2B, and BN2T Islander and BN2A Mk III

Trislander series airplanes, certificated in any category, that are

equipped with a nose wheel steering disconnect system with either a

Modification NB/M/503 or Modification NB/M/733 nose undercarriage

unit.

Compliance: Required within the next 100 hours time-in-service

(TIS), unless already accomplished, and thereafter at intervals not

to exceed 100 hours TIS.

To prevent failure of the nose wheel steering system because of

a cracked drive ring, which could result in the inability to move

the rudder pedals, accomplish the following:

(a) Visually inspect the nose wheel steering drive ring for

cracks in accordance with the ACTION section of Pilatus Britten-

Norman Service Bulletin No. BN-2/SB.214, Issue 1, dated September

23, 1993. Prior to further flight, replace any cracked nose wheel

steering drive ring in accordance with the applicable maintenance

manual.

(b) Special flight permits may be issued in accordance with

Secs. 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.

(c) An alternative method of compliance or adjustment of the

initial or repetitive compliance time that provides an equivalent

level of safety may be approved by the Manager, Brussels Aircraft

Certification Office, FAA, Europe, Africa, and Middle East Office,

c/o American Embassy, B-1000 Brussels, Belgium. The request should

be forwarded through an appropriate FAA Maintenance Inspector, who

may add comments and then send it to the Manager, Brussels Aircraft

Certification Office.

Note: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Brussels Aircraft Certification Office.

(d) 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 October 19,

1994.

John R. Colomy,

Acting Manager, Small Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-26371 Filed 10-24-94; 8:45 am]

BILLING CODE 4910-13-U