[Federal Register Volume 62, Number 65 (Friday, April 4, 1997)]
[Proposed Rules]
[Pages 16113-16115]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-8700]


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Proposed Rules
                                                Federal Register
________________________________________________________________________

This section of the FEDERAL REGISTER contains notices to the public of 
the proposed issuance of rules and regulations. The purpose of these 
notices is to give interested persons an opportunity to participate in 
the rule making prior to the adoption of the final rules.

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Federal Register / Vol. 62, No. 65 / Friday, April 4, 1997 / Proposed 
Rules

[[Page 16113]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-178-AD]
RIN 2120-AA64


Airworthiness Directives; Jetstream Model ATP Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Jetstream Model ATP 
airplanes. This proposal would require modification of the hydraulic 
system, and a revision to the Airplane Flight Manual (AFM) to include 
revised procedures for lowering the landing gear. This proposal is 
prompted by a report of uncommanded application of the brakes when the 
direct current (DC) hydraulic pump was selected ON with the main 
hydraulic system operative; this situation was caused by build-up of 
back pressure in the brake supply and hydraulic return systems. The 
actions specified by the proposed AD are intended to prevent 
uncommanded application of the brakes during landing, as a result of 
the build-up of back pressure.

DATES: Comments must be received by May 15, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-178-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays.
    The service information referenced in the proposed rule may be 
obtained from Jetstream Aircraft, Inc., 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) 227-1149.

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 96-NM-178-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. 96-NM-178-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The Civil Aviation Authority (CAA), which is the airworthiness 
authority for the United Kingdom, notified the FAA that an unsafe 
condition may exist on certain Jetstream Model ATP airplanes. The CAA 
advises that it has received a report of uncommanded application of the 
brakes when the direct current (DC) hydraulic pump of the auxiliary 
hydraulic system was selected ON with the main hydraulic system 
operative. The cause has been attributed to the build-up of back 
pressure in the brake supply and hydraulic return systems, as a result 
of installation of Jetstream Modification 10303A. (The existing design 
of Modification 10303A does not account for the fact that the auxiliary 
hydraulic system may be operated while the main hydraulic system is 
operating.) Build-up of back pressure in the brake supply and hydraulic 
return systems, if not corrected, could result in uncommanded 
application of the brakes during landing.

Explanation of Relevant Service Information

    Jetstream has issued Service Bulletin ATP-29-12, dated September 9, 
1995, which describes procedures for revisions to the Emergency and 
Abnormal Procedures Sections of the Airplane Flight Manual (AFM) to 
include revised procedures for lowering the landing gear. (Paragraph 
1.K. of the service bulletin references Temporary Revision No. T/52 as 
an additional source of service information for revising the AFM. This 
particular Temporary Revision applies to airplanes of U.S. registry.)
    The service bulletin also describes procedures for modification of 
the hydraulic system. The modification involves:
    1. Connecting the auxiliary hydraulic reservoir feed to the main 
hydraulic return system, thus eliminating the need for a check valve 
(HTE 510013) and its associated piping;
    2. Connecting the existing feed line of the auxiliary reservoir 
directly to the pressure bleed line of the brake master cylinder;
    3. Installing a non-return valve between the change-over isolation 
valve and the main pressure manifold; and
    4. Removing the bypass pipeline of the landing gear. Accomplishment 
of the modification will prevent

[[Page 16114]]

uncommanded application of the brakes during landing when the DC 
hydraulic pump is selected ON with the main hydraulic system operative.
    The CAA classified this service bulletin as mandatory and issued 
British airworthiness directive 001-09-095, dated September 1995, in 
order to assure the continued airworthiness of these airplanes in the 
United Kingdom.

FAA's Conclusions

    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, and determined 
that AD action is necessary for products of this type design that are 
certificated for operation in the United States.

Explanation of Requirements of Proposed Rule

    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 require modification of the 
hydraulic system. The proposed AD also would require revisions to the 
Emergency and Abnormal Procedures Sections of the FAA-approved AFM to 
include revised procedures for lowering the landing gear. The actions 
would be required to be accomplished in accordance with the service 
bulletin described previously.

Cost Impact

    The FAA estimates that 10 Jetstream Model ATP airplanes of U.S. 
registry would be affected by this proposed AD.
    It would take approximately 25 work hours per airplane to 
accomplish the proposed modification, at an average labor rate of $60 
per work hour. Required parts will be provided by the manufacturer at 
no cost to the operator. Based on these figures, the cost impact of the 
modification proposed by this AD on U.S. operators is estimated to be 
$15,000, or $1,500 per airplane.
    It would take approximately 1 work hour per airplane to accomplish 
the proposed AFM revisions, at an average labor rate of $60 per work 
hour. Based on these figures, the cost impact of the AFM revisions 
proposed by this AD on U.S. operators is estimated to be $600, or $60 
per airplane.
    The cost impact figures discussed above are 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.

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 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 
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:

Jetstream Aircraft Limited: Docket 96-NM-178-AD.

    Applicability: Model ATP airplanes, having constructor's numbers 
2002 through 2063 inclusive; on which Jetstream Modification 10303A 
(Jetstream Service Bulletin ATP 32-41) has been installed; 
certificated in any category.

    'Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 (b) 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 uncommanded application of the brakes during landing, 
accomplish the following:
    (a) Within 60 days of the effective date of this AD, accomplish 
paragraphs (a)(1) and (a)(2) of this AD in accordance with Jetstream 
Service Bulletin ATP-29-12, dated September 9, 1995.
    (1) Modify the hydraulic system; and
    (2) Revise the Emergency and Abnormal Procedures Sections of the 
FAA-approved Airplane Flight Manual (AFM) to include the information 
specified in Temporary Revision No. T/52, Issue 1, dated August 16, 
1995, which introduces revised procedures for lowering the landing 
gear, as specified in the temporary revision; and operate the 
airplane in accordance with those limitations and procedures.

    Note 2: Paragraph 1.K. of Jetstream Service Bulletin ATP-29-12, 
dated September 9, 1995, references Temporary Revision No. T/52 as 
an additional source of service information for revising the AFM.

    Note 3: This may be accomplished by inserting a copy of 
Temporary Revision No. T/52 in the AFM. When this temporary revision 
has been incorporated into general revisions of the AFM, the general 
revisions may be inserted in the AFM, provided the information 
contained in the general revisions is identical to that specified in 
Temporary Revision No. T/52.

    (b) 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.

    (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

[[Page 16115]]

can be accomplished. Issued in Renton, Washington, on March 31, 
1997.
S. R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-8700 Filed 4-3-97; 8:45 am]
BILLING CODE 4910-13-U