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

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 96-CE-25-AD]

RIN 2120-AA64

Airworthiness Directives; Pilatus Britten-Norman Ltd. (formerly

Britten-Norman) BN-2A, BN-2B, and BN-2T 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

that would apply to Pilatus Britten-Norman Ltd. (Pilatus Britten-

Norman) BN-2A, BN-2B, and BN-2T series airplanes. The proposed AD would

require repetitively inspecting the junction of the torque link lug and

upper case of the main landing gear (MLG) torque link assemblies for

cracks, and replacing any MLG torque link assembly with a Modification

A39 MLG torque link assembly, either immediately when cracks are found

or after a certain period of time if cracks are not found. Replacing

all MLG torque link assemblies with Modification A39 MLG torque link

assemblies would eliminate the need for the repetitive inspections.

These proposed repetitive inspections are currently required by AD 86-

07-02 for the BN-2A, BN-2B, and BN-2T series airplanes, as well as the

BN2A MK. 111 series airplanes. There are no improved design parts for

the BN2A MK. 111 series airplanes. The Federal Aviation Administration

(FAA) is issuing in a separate action a proposed revision to AD 86-07-

02 to retain the repetitive inspection and replacement (if cracked)

requirements for the BN2A MK. 111 series airplanes. The actions

specified in the proposed AD are intended to prevent failure of the

main landing gear caused by cracks in the torque link area, which could

lead to loss of control of the airplane during landing operations.

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

ADDRESSES: Submit comments on the proposal in triplicate to the FAA,

Central Region, Office of the Assistant Chief Counsel, Attention: Rules

Docket No. 96-CE-25-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 Limited, 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: Mr. Tom Rodriguez, Program Officer,

Brussels Aircraft Certification Division, FAA, Europe, Africa, and

Middle East Office, c/o American Embassy, B-1000 Brussels, Belgium;

telephone (32 2) 508.2717; facsimile (32 2) 230.6899; or Mr. S.M.

Nagarajan, 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. 96-CE-25-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-25-AD, Room 1558, 601 E. 12th Street,

Kansas City, Missouri 64106.

Discussion

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. With this policy in

mind, the FAA conducted a review of existing AD's that apply to Pilatus

Britten-Norman BN-2A, BN-2B, BN-2T, and BN2A MK. 111 series airplanes.

Assisting the FAA in this review were (1) Pilatus Britten-Norman; (2)

the Regional Airlines Association (RAA); (3) the Civil Aviation

Authority of the

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United Kingdom; and (4) several operators of the affected airplanes.

From this review, the FAA has identified AD 86-07-02, Amendment 39-

5382, as one which falls under the FAA's aging aircraft policy. AD 86-

07-02 currently requires repetitively inspecting the junction of the

torque link lug and upper case of the main landing gear (MLG) torque

link assemblies for cracks on Pilatus Britten-Norman BN-2A, BN-2B, BN-

2T, and BN2A MK. 111 series airplanes, and replacing any cracked part.

Pilatus Britten-Norman has developed a modification that, when

incorporated, would eliminate the need for the repetitive inspection

requirement of AD 86-07-02 for the Pilatus Britten-Norman BN-2A, BN-2B,

and BN-2T series airplanes. The requirements of AD 86-07-02 should

still apply for the Pilatus Britten-Norman BN2A MK. 111 series

airplanes.

Applicable Service Information

Fairey Hydraulics Limited has issued Service Bulletin (SB) 32-4,

Issue 4, dated January 30, 1990, which applies to the Pilatus Britten-

Norman BN-2A, BN-2B, and BN-2T series airplanes. This SB includes

procedures for inspecting the junction of the torque link lug and upper

case of the MLG torque link assemblies, and installing new Modification

A39 MLG torque link assemblies. Pilatus Britten-Norman SB BN-2/SB.170,

Issue 4, dated November 16, 1990, references Fairey Hydraulic Limited

SB32-4, Issue 4, dated January 30, 1990.

The FAA's Determination

The FAA has examined all available information related to this

subject matter and has determined that:

AD action should be taken for the Pilatus Britten-Norman

BN-2A, BN-2B, and BN-2T series airplanes to require the installation of

Modification A39 MLG torque link assemblies. The repetitive inspections

of the junction of the torque link lug and upper case of the MLG torque

link assemblies would still be required until the improved parts are

installed; and

AD 86-07-02 should be revised to remove the BN-2A BN-2B,

and BN-2T series airplanes from the applicability of that AD, but

retain the actions for the BN2A MK. 111 series airplanes (this is being

proposed in a separate action).

Explanation of the Provisions of the Proposed AD

Since an unsafe condition has been identified that is likely to

exist or develop in other Pilatus Britten-Norman BN-2A, BN-2B, and BN-

2T series airplanes of the same type design, the proposed AD would

require repetitively inspecting the junction of the torque link lug and

upper case of the MLG torque link assemblies for cracks, and replacing

any MLG torque link assembly with a Modification A39 MLG torque link

assembly, either immediately when cracks are found or at a certain

period of time if cracks are not found. Installation of the improved

part would eliminate the need for the repetitive inspections.

Accomplishment of the proposed inspections and installation would be in

accordance with Fairey Hydraulics Limited SB 32-4, Issue 4, dated

January 30, 1990.

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 13

workhours per airplane to accomplish the proposed action (1 workhour

per inspection and 12 workhours for the installation), and that the

average labor rate is approximately $60 an hour. Parts cost

approximately $6,200 per airplane. Based on these figures, the total

cost impact of the proposed AD on U.S. operators is estimated to be

$781,760 or $6,980 per airplane.

The proposed inspections are currently required on the 112 affected

airplanes by AD 86-07-02. The proposed AD would not require any

additional inspection requirements over that already required by AD 86-

07-02. In addition, the cost figures referenced above are based on the

presumption that no affected airplane operator has incorporated the

proposed inspection-terminating installation. Pilatus Britten-Norman

does not know the number of parts distributed to the affected airplane

owners/operators. Numerous sets of parts were sent out to the owners/

operators of the affected airplanes, but over the years Pilatus

Britten-Norman has not retained these records.

The FAA's Aging Commuter 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

25 percent are operated in scheduled passenger service by 11 different

operators. A significant number of the remaining 75 percent are

operated in other forms of air transportation such as air cargo and air

taxi.

The proposed action would allow at least 1,000 hours TIS after the

effective date of the AD before mandatory accomplishment of the design

modification (upon the accumulation of 5,000 hours TIS or within the

next 1,000 hours TIS after the effective date of the AD, whichever is

later). 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 airplanes involved

in commercial operation would have to accomplish the proposed

modification within 5 to 10 calendar months (at the least) 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 (at the least) before the proposed modification would be

mandatory. The time it would take those in air cargo/air taxi

operations before the proposed action would be mandatory is unknown

because of the wide variation between each airplane used in this

service. The exact numbers would fall somewhere between the average for

commuter operators and private operators.

Regulatory Flexibility Determination and Analysis

The Regulatory Flexibility Act of 1980 (RFA) was enacted by

Congress to ensure that small entities are not unnecessarily or

disproportionally burdened by government regulations. The RFA requires

government agencies to determine whether rules would have a

``significant economic impact on a substantial number of small

entities,'' and, in cases where they would, conduct a Regulatory

Flexibility Analysis in which alternatives to the rule are considered.

FAA Order 2100.14A, Regulatory Flexibility Criteria and Guidance,

outlines FAA procedures and criteria for complying with the RFA. Small

entities are defined as small businesses and small not-for-profit

organizations that are independently owned and operated or airports

operated by small governmental jurisdictions. A ``substantial number''

is defined as a number that is not less than 11 and that is more than

one-third of the small entities subject to a proposed rule, or any

number of small entities judged to be substantial by the rulemaking

official. A ``significant economic impact'' is defined by an annualized

net compliance cost, adjusted for inflation, which is greater than a

threshold cost level for defined entity types.

The entities that would be affected by this AD are mostly in the

portion of Standard Industrial Classification (SIC)

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4512, Operators of Aircraft for Hire, classified as ``unscheduled.''

FAA Order 2100.14A sets the size threshold for small entities operating

aircraft in this category at nine or fewer aircraft owned and the

annualized cost thresholds of at least $4,975 (1996 dollars) for

unscheduled operators. A four-year life for the torque link assembly

and capital cost of 15-percent would establish an annualized cost of

$2,445 (1996 dollars). This is less than 50-percent of the threshold

cost of $4,975 per year. In order to incur costs of at least $4,975, an

entity would have to operate three or more of the airplanes referenced

in the proposed AD. FAA data shows that only five small entities

operate three or more of these airplanes. In addition, this data shows

that approximately 60 entities operate the airplanes referenced in the

proposed AD, but that only 15 of these entities (one-fourth) operate

two or more of these airplanes.

Based on this information, less than one-third of the entities

would incur significant operating costs under FAA Order 2100.14A.

Therefore, the proposed AD would not significantly affect a number of

small entities.

A copy of the full Cost Analysis and Regulatory Flexibility

Determination for the proposed action may be examined at the FAA,

Central Region, Office of the Assistant Chief Counsel, Attention: Rules

Docket No. 96-CE-25-AD, Room 1558, 601 E. 12th Street, Kansas City,

Missouri.

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 USC 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: Docket No. 96-CE-25-AD.

Applicability: Models BN-2, BN-2A, BN-2A-3, BN-2A-6, BN-2A-8,

BN-2A-2, 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, and BN-2T airplanes (all serial

numbers), 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 (f) 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 as indicated after the effective date of

this AD, unless already accomplished.

To prevent failure of the main landing gear caused by cracks in

the torque link assembly area, which could lead to loss of control

of the airplane during landing operations, accomplish the following:

(a) Prior to further flight after the effective date of this AD

or within the next 100 hours time-in-service (TIS) after the last

inspection required by AD 86-07-02, whichever occurs later, and

thereafter at intervals not to exceed 100 hours TIS until the

installations required by paragraph (c) of this AD are accomplished,

inspect the junction of the torque link lug and upper case of all

main landing gear (MLG) torque link assemblies for cracks (using a

10-power magnifying glass or by dye penetrant methods). Accomplish

these inspections in accordance with the ACCOMPLISHMENT INSTRUCTIONS

section of Fairey Hydraulics Limited Service Bulletin (SB) 32-4,

Issue 4, dated January 30, 1990. Pilatus Britten-Norman SB BN-2/

SB.170, Issue 4, November 16, 1990, references this service

bulletin.

Note 2: These inspections were initially a part of AD 86-07-02,

which applied to the BN2A MK. 111 series airplanes as well as the

airplanes affected by this AD. The ``prior to further flight after

the effective date of this AD'' compliance time was the original

initial compliance time of AD 86-07-02, and is being retained to

provide credit and continuity for already-accomplished and future

inspections.

(b) If any cracks are found during any of the inspections

required by this AD, prior to further flight, replace the MLG torque

link assembly with a Modification A39 MLG torque link assembly in

accordance with the ACCOMPLISHMENT INSTRUCTIONS section of Fairey

Hydraulics Limited SB No. 32-4, Issue 4, dated January 30, 1990.

(1) Repetitive inspections are no longer required when all MLG

torque assemblies are replaced with Modification A39 MLG torque link

assemblies.

(2) Repetitive inspections may no longer be required on one MLG

torque assembly, but still be required on another if all haven't

been replaced with a Modification A39 MLG torque link assembly.

(c) Upon the accumulation of 5,000 hours TIS or within the next

1,000 hours TIS after the effective date of this AD, whichever

occurs later, unless already accomplished as specified in paragraph

(b) of this AD, replace each MLG torque link assembly with a

Modification A39 MLG torque link assembly in accordance with of the

ACCOMPLISHMENT INSTRUCTIONS section of Fairey Hydraulics Limited SB

No. 32-4, Issue 4, dated January 30, 1990.

(d) The intervals between the repetitive inspections required by

this AD may be adjusted up to 10 percent of the specified interval

to allow accomplishing these actions along with other scheduled

maintenance on the airplane.

(e) 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 inspection requirements of this AD can be accomplished.

(f) 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, Middle East office, FAA, c/o

American Embassy, 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 Division.

Note 3: Information concerning the existence of approved

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

obtained from the Brussels Aircraft Certification Division.

(g) All persons affected by this directive may obtain copies of

the documents referred to herein upon request to Fairey Hydraulics

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Limited, Claverham, Bristol, England; or Pilatus Britten-Norman

Limited, Bembridge, Isle of Wight, United Kingdom PO35 5PR, as

applicable; or may examine these documents 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 24, 1997.

Michael Gallagher,

Manager, Small Airplane Directorate, Aircraft Certification Service.

[FR Doc. 97-5471 Filed 3-5-97; 8:45 am]

BILLING CODE 4910-13-U