[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: 94-16405]
[[Page Unknown]]
[Federal Register: July 11, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 94-NM-75-AD; Amendment 39-8967; AD 94-14-19]
Airworthiness Directives; de Havilland Model DHC-7 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-7 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-75-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-7 series
airplanes. Transport Canada Aviation 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.
De Havilland, Inc., has issued Alert Service Bulletin S.B. A7-32-
97, dated November 10, 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-94-04, 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 7/
2516) 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.
The FAA is considering the issuance of parallel rulemaking action
to address the same unsafe condition on Model DHC-8-100 series
airplanes.
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-75-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:
94-14-19 de Havilland, Inc.: Amendment 39-8967. Docket 94-NM-75-AD.
Applicability: Model DHC-7 series airplanes; serial numbers 003
through 110 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 landing gear retraction 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. A7-32-97,
dated November 10, 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 5,400 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 5,400 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 5,400 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 5,400 hours time-in-service.
(b) Replacement of the hydraulic selector valve, part number
57420 or 57420-3, with an improved valve (Modification 7/2516), 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. A7-32-97, dated
November 10, 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. 94-16405 Filed 7-8-94; 8:45 am]
BILLING CODE 4910-13-U
