[Federal Register Volume 59, Number 241 (Friday, December 16, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-30801]
[[Page Unknown]]
[Federal Register: December 16, 1994]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 94-NM-210-AD; Amendment 39-9097; AD 94-26-01]
Airworthiness Directives; Learjet Model 24, 25, 31, 35, 36, and
55 Series Airplanes, and Learjet Model 28 and 29 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 Learjet Model 24, 25, 31, 35, 36, and 55
series airplanes, and Learjet Model 28 and 29 airplanes. This action
requires a revision to the Limitations Section of the FAA-approved
Airplane Flight Manual (AFM) to prohibit flight above an altitude of
41,000 feet. This action also provides optional terminating action for
that AFM revision. This amendment is prompted by a report of failure of
a safety valve in the pressurization system on a Learjet Model 31A
airplane and reports of cracks found in the poppets of certain outflow/
safety valves due to an improper molding process. The actions specified
in this AD are intended to prevent such cracking and subsequent failure
of the valves, which could result in rapid decompression of the
airplane.
DATES: Effective January 3, 1995.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of January 3, 1995.
Comments for inclusion in the Rules Docket must be received on or
before February 14, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 94-NM-210-AD, 1601 Lind Avenue SW., Renton,
Washington 98055-4056.
FOR FURTHER INFORMATION CONTACT: Walter Eierman, Aerospace Engineer,
Systems and Equipment Branch, ANM-131L, FAA, Transport Airplane
Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount
Boulevard, Lakewood, California 90712; telephone (310) 627-5336; fax
(310) 627-5210.
SUPPLEMENTARY INFORMATION: Recently, the FAA received a report of
failure of a safety valve in the pressurization system on a Learjet
Model 31A airplane. Failure of the valve resulted in depressurization
of the cabin. Investigation revealed that the poppets of certain
outflow/safety valves were cracked. These discrepant valves, including
the safety valve installed on the incident airplane, had been
manufactured since January 1, 1989. Certain valves manufactured since
that date have been found to be susceptible to cracking due to an
improper molding process. Cracking in the poppets of the outflow/safety
valves in the pressurization system can result in an open valve with an
effective flow area of 4.4 square inches; additionally, the valve may
close and remain closed. These conditions, if not corrected, could
result in rapid decompression of the airplane.
The FAA has reviewed and approved Allied Signal Aerospace Alert
Service Bulletins 130406-21-A4011, Revision 2, dated September 28,
1994, and 102850-21-A4021, Revision 2, dated October 6, 1994. These
alert service bulletins describe procedures for replacement of certain
outflow/safety valves in the pressurization system with serviceable
valves. Further, the alert service bulletins recommend that the maximum
altitude for operation of airplanes that may be equipped with these
outflow/safety valves be limited to 41,000 feet as an interim measure
until the affected valves are replaced.
Since an unsafe condition has been identified that is likely to
exist or develop on other products of the same type design, this AD is
being issued to prevent rapid decompression of the airplane. This AD
requires a revision to the Limitations Section of the FAA-approved
Airplane Flight Manual (AFM) to prohibit flight above an altitude of
41,000 feet. This AD also provides for replacement of certain outflow/
safety valves in the pressurization system as optional terminating
action for the AFM revision.
This is considered to be interim action. The FAA is considering
further rulemaking action to supersede this AD to require replacement
of certain outflow/safety valves within 18 months. However, the
proposed compliance time for the replacement is sufficiently long so
that notice and time for public comment would not be impracticable.
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 rule must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 94-NM-210-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 that it 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:
94-26-01 Learjet: Amendment 39-9097. Docket 94-NM-210-AD.
Applicability: Model 24, 25, 31, 35, 36, and 55 series
airplanes, and Model 28 and 29 airplanes; equipped with Allied
Signal outflow/safety valves, number 130406-1 or 102850-5; as
identified in Allied Signal Aerospace Alert Service Bulletin 130406-
21-A4011, Revision 2, dated September 28, 1994; or 102850-21-A4021,
Revision 2, dated October 6, 1994; certificated in any category.
Compliance: Required as indicated, unless accomplished
previously.
To prevent rapid decompression of the airplane due to cracking
and subsequent failure of certain outflow/safety valves, accomplish
the following:
(a) Within 30 days after the effective date of this AD, revise
the Limitations 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.
``Operation of the airplane at any altitude above 41,000 feet is
prohibited.''
(b) Replacement of outflow/safety valves, part numbers 130406-1
and 102850-5, as identified in Allied Signal Aerospace Alert Service
Bulletin 130406-21-A4011, Revision 2, dated September 28, 1994, or
102850-21-A4021, Revision 2, dated October 6, 1994, as applicable;
with a serviceable part in accordance with the procedures described
in the applicable alert service bulletin; constitutes terminating
action for the AFM limitation required by paragraph (a) of this AD.
Following such replacement, that AFM limitation may be removed from
the AFM.
(c) As of the effective date of this AD, no person shall install
an outflow/safety valve, part number 130406-1 or 102850-5, as
identified in Allied Signal Aerospace Alert Service Bulletin 130406-
21-A4011, Revision 2, dated September 28, 1994, or 102850-21-A4021,
Revision 2, dated October 6, 1994, as applicable; on any airplane
unless that valve is considered to be serviceable in accordance with
the specifications contained in the Accomplishment Instructions of
the applicable alert service bulletin.
(d) 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, Los Angeles Aircraft Certification
Office (ACO), FAA, Transport Airplane Directorate. Operators shall
submit their requests through an appropriate FAA Principal
Operations Inspector, who may add comments and then send it to the
Manager, Los Angeles ACO.
Note: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Los Angeles ACO.
(e) Special flight permits may be issued in accordance with
Secs. 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.
(f) The replacement shall be done in accordance with Allied
Signal Aerospace Alert Service Bulletin 130406-21-A4011, Revision 2,
dated September 28, 1994; or Allied Signal Aerospace Alert Service
Bulletin 102850-21-A4021, Revision 2, dated October 6, 1994; as
applicable. 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 Allied Signal, Inc.,
Controls & Accessories, 11100 N. Oracle Road, Tucson, Arizona 85737-
9588; telephone (602) 469-1000. Copies may be inspected at the FAA,
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington; or at the FAA, Transport Airplane Directorate, Los
Angeles Aircraft Certification Office, 3960 Paramount Boulevard,
Lakewood, California; or at the Office of the Federal Register, 800
North Capitol Street, NW., suite 700, Washington, DC.
(g) This amendment becomes effective on January 3, 1995.
Issued in Renton, Washington, on December 9, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 94-30801 Filed 12-15-94; 8:45 am]
BILLING CODE 4910-13-U
