Airworthiness Directives; Jetstream Aircraft Limited Model 4101 Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-25-AD]

Airworthiness Directives; Jetstream Aircraft Limited Model 4101

Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing

airworthiness directive (AD), applicable to certain Jetstream Model

4101 airplanes, that currently requires inspections to detect damage of

the ball bearings in the aileron quadrants, replacement of damaged ball

bearings with new ball bearings, and adjustment to the secondary stops.

This action would require installation of new swivel bearings in the

aileron quadrants, which would terminate the inspection requirement.

This proposal is prompted by the development of a modification that

eliminates the need to inspect repetitively. The actions specified by

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

aileron quadrants, which could result in reduced controllability of the

airplane.

DATES: Comments must be received by June 29, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-103,

Attention: Rules Docket No. 94-NM-25-AD, 1601 Lind Avenue SW., Renton,

Washington 98055-4056. Comments may be inspected at this location

between 9 a.m. and 3 p.m., Monday through Friday, except Federal

holidays.

The service information referenced in the proposed rule may be

obtained from Jetstream Aircraft, Incorporated, P.O. Box 16029, Dulles

International Airport, Washington, DC 20041-6029. This information may

be examined at the FAA, Transport Airplane Directorate, 1601 Lind

Avenue SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: William Schroeder, Aerospace Engineer,

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

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

227-2148; fax (206) 227-1320.

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 shall 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 summarizing 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 Number 94-NM-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, Transport Airplane Directorate, ANM-103, Attention: Rules

Docket No. 94-NM-25-AD, 1601 Lind Avenue SW., Renton, Washington 98055-

4056.

Discussion

On March 3, 1994, the FAA issued AD 93-25-10, Amendment 39-8849 (59

FR 11531, March 11, 1994), applicable to certain Jetstream Model 4101

airplanes, to require inspections to detect damage of the ball bearings

in the aileron quadrants, replacement of damaged ball bearings with new

ball bearings, and adjustment to the secondary stops. That action was

prompted by a report that an in-flight failure of a ball bearing in a

quadrant in the pilot's aileron control system caused abnormal backlash

of the pilot's aileron control. The requirements of that AD are

intended to prevent reduced controllability of the airplane.

Since the issuance of that AD, Jetstream has developed new swivel

bearings that allow greater swivel action, which would significantly

decrease the likelihood of abnormal backlash of the aileron control due

to bearing failure. Bearing failure in the aileron quadrants, if not

corrected, could result in reduced controllability of the airplane.

Jetstream has issued Service Bulletin J41-27-027, dated January 17,

1994, that describes procedures for installation of swivel bearings in

the left and right aileron quadrants (Modification JM41307A).

Jetstream has also issued Revision 2 of Service Bulletin J41-A-27-

026, dated January 17, 1994. The inspection procedures described in

this revision are identical to those described in Revision 1 of the

service bulletin (which was referenced in AD 93-25-10). The only change

effected by Revision 2 is to reference the modification described in

Service Bulletin J41-27-027 as terminating action for the inspections

of the bearings in the aileron quadrants and adjustment to the

secondary stops described in Service Bulletin J41-A-27-026. The CAA

classified this service bulletin as mandatory in order to assure the

continued airworthiness of these airplanes in the United Kingdom.

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 and the

applicable bilateral airworthiness agreement. Pursuant to this

bilateral airworthiness agreement, the Civil Aviation Authority (CAA),

which is the airworthiness authority for the United Kingdom, 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 on other airplanes of the same type design registered

in the United States, the proposed AD would supersede AD 93-25-10 to

require installation of new swivel bearings in the left and right

aileron quadrants (Modification JM41307A) as terminating action for the

currently required inspections. The actions would be required to be

accomplished in accordance with the service bulletins described

previously.

Paragraphs (a) and (b) of this proposal have been revised to

reference Revision 2 of Service Bulletin J41-A-27-026, dated January

17, 1994, as an additional source of service information for

accomplishing the inspections of the bearings in the aileron quadrants

and adjustment to the secondary stops.

The FAA estimates that 8 airplanes of U.S. registry would be

affected by this proposed AD.

The inspections that were previously required by AD 93-25-10, and

retained in this proposal, take approximately 1 work hour per airplane

to accomplish, at an average labor rate of $55 per work hour. Based on

these figures, the total cost impact of these inspection requirements

on U.S. operators is estimated to be $440, or $55 per airplane, per

inspection cycle.

The adjustment to the secondary stops that were previously required

by AD 93-25-10, and retained in this proposal, take approximately 1

work hour per airplane to accomplish, at an average labor rate of $55

per work hour. Based on these figures, the total cost impact of this

adjustment requirement on U.S. operators is estimated to be $440, or

$55 per airplane. The FAA estimates that all affected U.S. operators

have already accomplished this action; therefore, the future cost

impact of this requirement is minimal.

The installation of new swivel bearings (Modification JM41307A)

that would be required by this proposal would take approximately 10

work hours per airplane to accomplish, at an average labor rate of $55

per work hour. Required parts would be provided by the manufacturer at

no cost to the operator. Based on these figures, the total cost impact

of the modification requirement of this proposal on U.S. operators is

estimated to be $4,400, or $550 per airplane.

The total cost impact figure discussed above is based on

assumptions that no operator has yet accomplished any of the proposed

requirements of this AD action, and that no operator would accomplish

those actions in the future if this AD were not adopted.

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 proposed

regulation: (1) Is not a ``significant regulatory action'' under

Executive Order 12866; (2) is not a ``significant rule'' under the 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 is contained 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 14

CFR part 39 of the Federal Aviation Regulations 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 removing amendment 39-8849 (59 FR

11531, March 11, 1994), and by adding a new airworthiness directive

(AD), to read as follows:

Jetstream Aircraft Limited: Docket 94-NM-25-AD. Supersedes AD 93-25-

10, Amendment 39-8849.

Applicability: Model 4101 airplanes having constructors numbers

41004 and subsequent on which Modification JM41307A or JM41307B has

not been installed previously; certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent failure of the bearings in the aileron quadrants,

which could result in reduced controllability of the airplane,

accomplish the following:

(a) Within 7 days after March 28, 1994 (the effective date of AD

93-25-10, Amendment 39-8849), perform a detailed visual inspection

to detect damage of the bearings in the aileron quadrant in the

pilot's and co-pilot's aileron control, in accordance with Jetstream

Aircraft Limited Alert Service Bulletin J41-A-27-026, Revision 1,

dated December 7, 1993; or Revision 2, dated January 17, 1994.

(1) If no damaged bearing is found, repeat the inspection,

thereafter, at intervals not to exceed 7 days.

(2) If any damaged bearing is found, prior to further flight,

replace the damaged bearing with a new bearing in accordance with

the service bulletin, and repeat the inspection, thereafter, at

intervals not to exceed 7 days.

Note 1: Paragraph (a) of this AD restates the requirement for an

initial and repetitive inspections contained in paragraph (a) of AD

93-25-10. Therefore, for operators that have previously accomplished

at least the initial inspection in accordance with AD 93-25-10,

paragraph (a) of this AD requires that the next scheduled inspection

be performed within 7 days after the last inspection performed in

accordance with paragraph (a) of AD 93-25-10.

(b) Within 7 days after March 28, 1994 (the effective date of AD

93-25-10, Amendment 39-8849), adjust the aileron secondary stop in

the pilot's and co-pilot's aileron control system in accordance with

Jetstream Aircraft Limited Alert Service Bulletin J41-A-27-026,

Revision 1, dated December 7, 1993; or Revision 2, dated January 17,

1994.

Note 2: Paragraph (b) of this AD restates the requirement to

adjust the aileron secondary stop contained in paragraph (b) of AD

93-25-10. As allowed by the phrase ``unless accomplished

previously,'' if that requirement of AD 93-25-10 has been

accomplished previously, this AD does not require that it be

repeated.

(c) Within 7 days after March 28, 1994 (the effective date of AD

93-25-10, Amendment 39-8849), revise the Abnormal Procedures Section

of the FAA-approved Airplane Flight Manual (AFM) to include the

following. This may be accomplished by inserting a copy of this AD

in the AFM.

``Where abnormal aileron control backlash is experienced by one

pilot, the other pilot should assume control of the aircraft without

using the disconnect facility. The disconnect facility should only

be used in accordance with published procedures in cases of control

restrictions or jamming.''

Note 3: Paragraph (c) of this AD restates the requirement for an

AFM revision contained in paragraph (c) of AD 93-25-10. As allowed

by the phrase ``unless accomplished previously,'' if that

requirement of AD 93-25-10 has been accomplished previously, this AD

does not require that it be repeated.

(d) Within 180 hours time-in-service after the effective date of

this AD, install new swivel bearings in the left and right aileron

quadrants (Modification JM41307A) in accordance with Jetstream

Service Bulletin J41-27-027, dated January 17, 1994. Accomplishment

of this modification constitutes terminating action for the

requirements of this AD. The AFM revision required by paragraph (c)

of this AD may be removed following accomplishment of this

modification.

(e) 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 4: Information concerning the existence of approved

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

obtained from the Standardization Branch, ANM-113.

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

Federal Aviation Regulations (FAR) 21.197 and 21.199 to operate the

airplane to a location where the requirements of this AD can be

accomplished.

Issued in Renton, Washington, on April 28, 1994.

James V. Devany,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-10643 Filed 5-3-94; 8:45 am]

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