[Federal Register Volume 59, Number 131 (Monday, July 11, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-16406]


[[Page Unknown]]

[Federal Register: July 11, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-NM-76-AD; Amendment 39-8966; AD 94-14-18]

 

Airworthiness Directives; de Havilland Model DHC-8-100 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to certain de Havilland Model DHC-8-100 series airplanes. 
This action requires repetitive inspections of the hydraulic selector 
valve to determine the rate of leakage of hydraulic fluid, and 
replacement of certain valves with serviceable valves, if necessary. 
This AD also provides an optional terminating action for the repetitive 
inspections. This amendment is prompted by a report of pilot valve 
leakage of hydraulic fluid in a landing gear selector valve on a Model 
DHC-7 series airplane. The actions specified in this AD are intended to 
prevent inadvertent retraction of the landing gear in the event of a 
low voltage condition at the selector valve down solenoid.

DATES: Effective July 26, 1994. The incorporation by reference of 
certain publications listed in the regulations is approved by the 
Director of the Federal Register as of July 26, 1994.
    Comments for inclusion in the Rules Docket must be received on or 
before September 9, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 94-NM-76-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056.
    The service information referenced in this AD may be obtained from 
de Havilland, Inc., Garratt Boulevard, Downsview, Ontario M3K 1Y5, 
Canada. This information may be examined at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, 
Engine and Propeller Directorate, New York Aircraft Certification 
Office, 181 South Franklin Avenue, room 202, Valley Stream, New York; 
or at the Office of the Federal Register, 800 North Capitol Street NW., 
suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Danko Kramar, Aerospace Engineer, 
Systems and Equipment Branch, ANE-173, FAA, Engine and Propeller 
Directorate, New York Aircraft Certification Office, 181 South Franklin 
Avenue, room 202, Valley Stream, New York 11581; telephone (516) 791-
6428; fax (516) 791-9024.

SUPPLEMENTARY INFORMATION: Transport Canada Aviation, which is the 
airworthiness authority for Canada, recently notified the FAA that an 
unsafe condition may exist on certain de Havilland Model DHC-8-100 
series airplanes. Transport Canada advises that it has received a 
report of pilot valve leakage of hydraulic fluid in a landing gear 
selector valve on a Model DHC-7 series airplane. The cause of this 
leakage has been attributed to a faulty seal. Such leakage, if combined 
with a low voltage condition at the selector valve down solenoid, could 
result in inadvertent retraction of the landing gear.
    Since the same selector valve that is used on Model DHC-7 series 
airplanes is installed on Model DHC-8-100 series airplanes, the FAA 
finds that the latter airplane model also is subject to the addressed 
unsafe condition. The FAA may consider issuance of parallel rulemaking 
action to address this unsafe condition on Model DHC-7 series 
airplanes.
    De Havilland, Inc., has issued Alert Service Bulletin S.B. A8-32-
117, dated December 11, 1992, that describes procedures for repetitive 
inspections of the hydraulic selector valve to determine the rate of 
leakage of hydraulic fluid, and replacement of certain valves with 
serviceable valves, if necessary. Transport Canada Aviation classified 
this service bulletin as mandatory and issued Canadian Airworthiness 
Directive CF-94-05, dated March 16, 1994, in order to assure the 
continued airworthiness of these airplanes in Canada.
    De Havilland, Inc., also has developed a valve (Modification 8/
0530) that incorporates several improvements to minimize pilot valve 
leakage. This valve is equipped with an improved spring that keeps the 
valve firmly seated. The improved valve incorporates a reduced rate of 
opening and further restricts the orifice leading to the landing gear 
actuators. Replacement of certain valves with these improved valves 
will minimize the possibility of inadvertent landing gear retraction.
    This airplane model is manufactured in Canada 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, Transport Canada Aviation has kept 
the FAA informed of the situation described above. The FAA has examined 
the findings of Transport Canada Aviation, 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, this AD is being issued to prevent inadvertent 
retraction of the landing gear in the event of a low voltage condition 
at the selector valve down solenoid. This AD requires repetitive 
inspections of the hydraulic selector valve to determine the rate of 
leakage of hydraulic fluid, and replacement of certain valves with 
serviceable valves, if necessary. This AD also provides an optional 
terminating action for the repetitive inspections. The actions are 
required to be accomplished in accordance with the alert service 
bulletin described previously.
    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 
AD 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-76-AD.'' The postcard will be date stamped and 
returned to the commenter.
    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.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and is not a ``significant regulatory action'' 
under Executive Order 12866. It has been determined further that this 
action involves an emergency regulation under DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979). If it is determined 
that this emergency regulation otherwise would be significant under DOT 
Regulatory Policies and Procedures, a final regulatory evaluation will 
be prepared and placed in the Rules Docket. A copy of it, if filed, 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. 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 the following new 
airworthiness directive:

94-14-18  de Havilland, Inc.: Amendment 39-8966. Docket 94-NM-76-AD.

    Applicability: Model DHC-8-100 series airplanes; serial numbers 
003 through 038 inclusive; equipped with landing gear selector 
valve, part number 57420 or 57420-3; certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent inadvertent retraction of the landing gear due to 
pilot valve leakage, accomplish the following:
    (a) Within 300 hours time-in-service after the effective date of 
this AD, inspect the hydraulic selector valve to determine the rate 
of leakage of hydraulic fluid, in accordance with the Accomplishment 
Instructions of de Havilland Alert Service Bulletin S.B. A8-32-117, 
dated December 11, 1992.
    (1) If the rate of leakage is 100 cubic centimeters (cc) per 
minute or less: Repeat the inspection required by paragraph (a) of 
this AD thereafter at intervals not to exceed 10,000 hours time-in-
service.
    (2) If the rate of leakage is more than 100 cc per minute, but 
less than 1,000 cc per minute: Within 300 hours time-in-service, 
replace the hydraulic selector valve with a serviceable valve in 
accordance with the alert service bulletin. Thereafter, repeat the 
inspection required by paragraph (a) of this AD at intervals not to 
exceed 10,000 hours time-in-service.
    (3) If the rate of leakage is 1,000 cc or more per minute, but 
less than 1,500 cc per minute: Within 50 hours time-in-service, 
replace the hydraulic selector valve with a serviceable valve in 
accordance with the alert service bulletin. Thereafter, repeat the 
inspection required by paragraph (a) of this AD at intervals not to 
exceed 10,000 hours time-in-service.
    (4) If the rate of leakage is 1,500 cc or more per minute: Prior 
to further flight, replace the hydraulic selector valve with a 
serviceable valve in accordance with the alert service bulletin. 
Thereafter, repeat the inspection required by paragraph (a) of this 
AD at intervals not to exceed 10,000 hours time-in-service.
    (b) Replacement of the hydraulic selector valve, part number 
57420 or 57420-3, with an improved valve (Modification 8/0530), part 
number 57420-5, constitutes terminating action for the requirements 
of this AD.
    (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, New York Aircraft Certification 
Office (ACO), FAA, Engine and Propeller Directorate. Operators shall 
submit their requests through an appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, New York ACO.

    Note: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the New York ACO.

    (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 inspections and replacement shall be done in accordance 
with de Havilland Alert Service Bulletin S.B. A8-32-117, dated 
December 11, 1992. 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 de Havilland, 
Inc., Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. Copies 
may be inspected at the FAA, Transport Airplane Directorate, 1601 
Lind Avenue, SW., Renton, Washington; or at the FAA, Engine and 
Propeller Directorate, New York Aircraft Certification Office, 181 
South Franklin Avenue, room 202, Valley Stream, New York; or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.
    (f) This amendment becomes effective on July 26, 1994.

    Issued in Renton, Washington, on June 30, 1994.

Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-16406 Filed 7-8-94; 8:45 am]
BILLING CODE 4910-13-U