Airworthiness Directives; Fokker Model F27 Series Airplanes Equipped With Walter Kidde Nose Wheel Steering System

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-38-AD; Amendment 39-9941; AD 97-04-16]

RIN 2120-AA64

Airworthiness Directives; Fokker Model F27 Series Airplanes

Equipped With Walter Kidde Nose Wheel Steering System

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD),

applicable to certain Fokker Model F27 series airplanes, that requires

increasing the torque value of the bolt that connects the gearbox

housing assembly of the steering unit to the pivot bracket of the nose

landing gear (NLG). This amendment also requires that periodic

inspections of that torque value be incorporated into the FAA-approved

maintenance program. This amendment is prompted by several reports that

the dowel pins in the Walter Kidde nose wheel steering system were

found broken and/or had elongated holes due to a reduced torque value

of the subject bolt. The actions specified by this AD are intended to

prevent such a reduction in the torque value, which could result in

failure of the dowel pins in the Walter Kidde nose wheel steering

system; this situation could result in reduced controllability of the

airplane or the collapse of the NLG during landing.

DATES: Effective March 31, 1997.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of March 31, 1997.

ADDRESSES: The service information referenced in this AD may be

obtained from Fokker Aircraft USA, Inc., 1199 North Fairfax Street,

Alexandria, Virginia 22314. This information may be examined at the

Federal Aviation Administration (FAA), Transport Airplane Directorate,

Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the

Office of the Federal Register, 800 North Capitol Street, NW., suite

700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Ruth Harder, Aerospace Engineer,

Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206)

227-1721; fax (206) 227-1149.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39) to include an airworthiness

directive (AD) that is applicable to certain Fokker Model F27 series

airplanes was published in the Federal Register on July 29, 1996 (61 FR

39366). That action proposed to require increasing the torque value of

the bolt that connects the gearbox housing assembly of the steering

unit to the pivot bracket of the nose landing gear (NLG).

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

Support for the Proposal

One commenter supports the proposed rule.

Request to Withdraw Proposal

One commenter, a U.S. operator, requests that the proposal be

withdrawn because it is unnecessary. The commenter points out that the

proposed requirements previously were issued by Fokker both as a

service bulletin and a maintenance circular several years ago. This

commenter has already added the inspections to its maintenance program,

far in advance of any requirement by AD to do so. The commenter

contends that mandating the actions via an AD will ``only add an

administrative burden on an industry already overburdened with

administrative tasks, many of which are redundant.'' Instead of issuing

this AD, the commenter recommends that the proposed requirements be

added to the airlines' Operations Specifications, or merely have the

Principal Maintenance Inspectors for the affected airlines talk to the

operators about this issue. The commenter maintains that handling the

proposed requirements in some other way than by AD action would save

the affected operators a considerable amount of time and money.

The FAA does not concur with the commenter's request to withdraw

the proposal. The FAA acknowledges that the required actions specified

in this AD were contained in a manufacturer's service bulletin and

maintenance circular, both of which were released some time ago.

Prudent operators, such as the commenter, may have accomplished those

actions already. However, until an AD is issued, there is no legal

basis for requiring U.S. operators to comply with those actions. The AD

is the vehicle for ensuring, by law, that all affected operators

perform the necessary actions that will address the identified unsafe

condition. In light of this, the FAA has determined that this AD is

appropriate and warranted.

Further, the FAA is not convinced that issuance of this AD will add

a significant economic or administrative burden on operators who have

already accomplished the required actions, as the commenter suggests:

First, the FAA points out that there are currently only 34 U.S.-

registered airplanes that are affected by the AD.

Second, the compliance provision of the AD clearly states that

compliance is ``required as indicated, unless accomplished

previously.'' Therefore, operators who have already accomplished the

required actions need only make a single entry in their maintenance

logs to indicate compliance with the AD. Further, once the maintenance

program is changed to include the required periodic inspections, in

accordance with paragraph (b) of the AD, operators do not need to make

a maintenance log entry to show compliance with the AD every time those

inspections are accomplished thereafter. (A new Note 2 has been added

to the final rule to specify this.) Such procedures should

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not pose a serious burden on any operator.

Conclusion

After careful review of the available data, including the comments

noted above, the FAA has determined that air safety and the public

interest require the adoption of the rule with the changes previously

described. The FAA has determined that these changes will neither

increase the economic burden on any operator nor increase the scope of

the AD.

Cost Impact

The FAA estimates that 34 Fokker Model F27 series airplanes of U.S.

registry will be affected by this AD.

It will take approximately 2 work hours per airplane to accomplish

the required actions, at an average labor rate of $60 per work hour.

Based on these figures, the cost impact of this AD on U.S. operators is

estimated to be $4,080, or $120 per airplane.

The cost impact figure discussed above is based on assumptions that

no operator has yet accomplished any of the requirements of this AD

action, and that no operator would accomplish those actions in the

future if this AD were not adopted.

However, the FAA has been advised that one U.S. operator already

has accomplished the required actions on its 2 affected airplanes.

Therefore, the future cost impact of this AD is only $4,056.

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 final evaluation has been prepared for this action

and it is contained in the Rules Docket. A copy of it may be obtained

from 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 the following new

airworthiness directive:

97-04-16 Fokker: Amendment 39-9941. Docket 96-NM-38-AD.

Applicability: Model F27 series airplanes, serial numbers 10102

through 10692 inclusive; equipped with Walter Kidde nose wheel

steering system (steering unit gearbox housing assembly) having part

number 893954; 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 (c) 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, unless accomplished

previously.

To prevent a reduction in the torque value of the bolt in the

Walter Kidde nose wheel steering system, which could result in

reduced controllability of the airplane or the collapse of the nose

landing gear (NLG) during landing, accomplish the following:

(a) Within 500 flight hours after the effective date of this AD,

or within 4 months after the effective date of this AD, whichever

occurs first, tighten the bolt that connects the gearbox housing

assembly of the steering unit to the pivot bracket of the NLG to a

torque value of 700 to 800 inch-pounds, in accordance with Fokker

Service Bulletin F27/32-166, dated September 7, 1993.

(b) Within 30 days following accomplishment of paragraph (a) of

this AD, revise the FAA-approved maintenance program to include

periodic inspections of the torque value of the affected bolt, as

described in Fokker F27 Maintenance Circular No. 32-6, dated April

30, 1993; and, thereafter, comply with those requirements.

Note 2: Once the maintenance program is changed to include the

required periodic inspections, in accordance with this paragraph,

operators do not need to make a maintenance log entry to show

compliance with this AD every time those inspections are

accomplished thereafter.

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

compliance time that provides an acceptable level of safety may be

used if approved by the Manager, Standardization Branch, ANM-113,

FAA, Transport Airplane Directorate. Operators shall submit their

requests through an appropriate FAA Principal Maintenance Inspector,

who may add comments and then send it to the Manager,

Standardization Branch, ANM-113.

Note 3: Information concerning the existence of approved

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

obtained from the Standardization Branch, ANM-113.

(d) 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.

(e) The actions shall be done in accordance with Fokker Service

Bulletin F27/32-166, dated September 7, 1993; and Fokker F27

Maintenance Circular No. 32-6, dated April 30, 1993. 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 Fokker Aircraft USA, Inc., 1199

North Fairfax Street, Alexandria, Virginia 22314. Copies may be

inspected at the FAA, Transport Airplane Directorate, 1601 Lind

Avenue, SW., Renton, Washington; or at the Office of the Federal

Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(f) This amendment becomes effective on March 31, 1997.

Issued in Renton, Washington, on February 13, 1997.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 97-4201 Filed 2-21-97; 8:45 am]

BILLING CODE 4910-13-U