[Federal Register Volume 60, Number 238 (Tuesday, December 12, 1995)]
[Rules and Regulations]
[Pages 63617-63619]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-29300]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-NM-209-AD; Amendment 39-9447; AD 95-25-03]
Airworthiness Directives; Learjet Model 23, 24, 25, 35, and 36
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 23, 24, 25, 35, and 36
airplanes. This action requires repetitive inspections to detect
deterioration of both flapper valves of the tip tank in each wing of
the airplane, and various follow-on actions. This AD action also
requires replacing the flapper valves with new flapper valves, and
repetitively performing certain other follow-on actions. This amendment
is prompted by reports of imbalance of the fuel loads in the wings of
the airplane due to failed or cracked flapper valves. The actions
specified in this AD are intended to prevent significant reduction in
the lateral control of the airplane due to imbalance of the fuel loads
in the wings of the airplane.
DATES: Effective December 27, 1995.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of December 27, 1995.
Comments for inclusion in the Rules Docket must be received on or
before February 12, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 95-NM-209-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056.
The service information referenced in this AD may be obtained from
Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942. This
information may be examined at the FAA, Transport Airplane Directorate,
1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Wichita
Aircraft Certification Office, Small Airplane Directorate, 1801 Airport
Road, Room 100, Mid-Continent Airport, Wichita, Kansas; or at the
Office of the Federal Register, 800 North Capitol Street, NW., suite
700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Jeffrey Janusz, Aerospace Engineer,
Systems and Propulsion Branch, ACE-116W, FAA, Wichita Aircraft
Certification Office, Small Airplane Directorate, 1801 Airport Road,
Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316)
946-4148; fax (316) 946-4407.
SUPPLEMENTARY INFORMATION: Recently, the FAA has received several
reports of imbalance of the fuel loads in the wings of Learjet Model
23, 24, 25, 35, and 36 airplanes. Investigation reveals that the
[[Page 63618]]
flapper valves in the fuel tanks may deteriorate over a period of time,
which may result in failure of the valve hinge or cracking of the
circular portion of the valve. Further investigation indicates that
such failures and cracking may allow fuel to enter into the tip tanks
in the wings of the airplane. This condition, if not corrected, could
result in imbalance of the fuel loads in the wings of the airplane,
which can significantly reduce lateral control of the airplane.
The FAA has reviewed and approved Learjet Service Bulletins SB 23/
24/25-28-2 (for Model 23, 24, and 25 airplanes) and SB 35/36-28-10 (for
Model 35 and 36 airplanes), both dated October 6, 1995, which describe
procedures for a one-time inspection to detect deterioration of both
flapper valves of the tip tank in each wing of the airplane, and
various follow-on actions (which include inspecting the flapper valve
to ensure proper positioning of the valve, inspecting the conditions of
the screws that retain the flapper valve to the plate assembly, and
ensuring that the flapper valve completely covers the opening of the
tube and is seated against the tube). The service bulletins also
describe procedures for replacement of both flapper valves of the tip
tank in each wing with new flapper valves, and inspecting to verify
free movement of the flapper valve.
Since an unsafe condition has been identified that is likely to
exist or develop on other airplanes of the same type design, this AD is
being issued to prevent imbalance of fuel loads in the wings of the
airplane, which can significantly reduce lateral control of the
airplane. This AD requires that operators perform repetitive
inspections to detect deterioration of both flapper valves of the tip
tank in each wing of the airplane, and various follow-on actions (such
as, inspecting the flapper valve to ensure proper positioning of the
valve, inspecting the conditions of the screws that retain the flapper
valve to the plate assembly, ensuring that the flapper valve completely
covers the opening of the tube and is seated against the tube, and
inspecting to verify free movement of the flapper valve). The AD
requires that operators replace both flapper valves of the tip tank in
each wing of the airplane with new flapper valves, and repetitively
performing certain other follow-on actions. The actions are required to
be accomplished in accordance with the procedures in the service
bulletins described previously.
Operators should note that, although the service bulletins
recommend that certain follow-on actions be accomplished only once, the
FAA has determined that accomplishing these follow-on actions just one
time would not address the identified unsafe condition over the long
term. In developing the appropriate actions for this proposed AD, the
FAA considered not only the manufacturer's recommendation, but the
degree of urgency associated with addressing the subject unsafe
condition, the potential catastrophic consequences of the unsafe
condition, and the numerous reported incidents of unbalanced fuel
loads. In light of all of these factors, the FAA finds that certain
follow-on actions must be performed repetitively at intervals of 600
hours time-in-service to ensure continued operational safety of the
fleet.
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 95-NM-209-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 USC 106(g), 40101, 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
95-25-03 Learjet: Amendment 39-9447. Docket 95-NM-209-AD.
Applicability: Model 23, 24, and 25 airplanes, as listed in
Learjet Service Bulletin SB 23/24/25-28-2, dated October 6, 1995,
and Model 35 and 36 airplanes, as listed in Learjet Service Bulletin
35/36-28-10, dated October 6, 1995; certificated in any category.
[[Page 63619]]
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
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 use the authority
provided in paragraph (e) of this AD to request approval from the
FAA. This approval may address either no action, if the current
configuration eliminates the unsafe condition; or different actions
necessary to address the unsafe condition described in this AD. Such
a request should include an assessment of the effect of the changed
configuration on the unsafe condition addressed by this AD. In no
case does the presence of any modification, alteration, or repair
remove any airplane from the applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
Note 2: This AD references certain Learjet service bulletins for
applicability information, and inspection and replacement
procedures. This AD requires performing certain follow-on actions
repetitively, although the service bulletins specify accomplishing
these actions just once. Where there are differences between the AD
and the service bulletins, the AD prevails.
To prevent imbalance of the fuel loads in the wings of the
airplane, which can significantly reduce lateral control of the
airplane, accomplish the following:
(a) Within 50 hours time-in-service after the effective date of
this AD or prior to the accumulation of 600 hours time-in-service
since installation of the flapper valve, whichever occurs later:
Perform an inspection to detect deterioration (such as cracks, cuts,
breaks, splits, or warpage) of both flapper valves of the tip tank
in each wing, in accordance with either Learjet Service Bulletin SB
23/24/25-28-2, dated October 6, 1995 (for Model 23, 24, and 25
airplanes), or Learjet Service Bulletin SB 35/36-28-10, dated
October 6, 1995 (for Model 35 and 36 airplanes); as applicable.
Repeat this inspection thereafter at intervals not to exceed 600
hours time-in-service.
(1) If no deterioration of the flapper valve is detected, prior
to further flight, inspect the flapper valve to ensure proper
positioning, inspect the condition of the screws that retain the
flapper valve to the plate assembly to ensure that the flapper valve
is secure, inspect to ensure that the flapper valve completely
covers the opening of the tube and is seated against the tube, and
inspect the flapper valve to verify that it moves freely; and
accomplish the follow-on corrective actions, if any discrepancy is
found. These actions shall be accomplished in accordance with the
applicable service bulletin.
(2) If any flapper valve is found to be deteriorated, prior to
further flight, replace it with a new flapper valve in accordance
with the applicable service bulletin.
(b) Except as provided in paragraph (c) of this AD, at the later
of the times specified in paragraphs (b)(1) and (b)(2) of this AD:
Replace both flapper valves of the tip tank in each wing with new
flapper valves in accordance with either Learjet Service Bulletin SB
23/24/25-28-2, dated October 6, 1995 (for Model 23, 24, and 25
airplanes), or Learjet Service Bulletin SB 35/36-28-10, dated
October 6, 1995 (for Model 35 and 36 airplanes); as applicable.
(1) Within 5 years since date of installation of the flapper
valve, or prior to the accumulation of 2,400 total hours time-in-
service on the flapper valve, whichever occurs earlier.
(2) Within 50 hours time-in-service after the effective date of
this AD.
(c) For airplanes on which the age and time-in-service of the
flapper valve cannot be determined: Within 50 hours time-in-service
after the effective date of this AD, replace both flapper valves of
the tip tank in each wing in accordance with either Learjet Service
Bulletin SB 23/24/25-28-2, dated October 6, 1995 (for Model 23, 24,
and 25 airplanes), or Learjet Service Bulletin SB 35/36-28-10, dated
October 6, 1995 (for Model 35 and 36 airplanes); as applicable.
(d) Within 600 hours time-in-service following replacement of
any flapper valve in accordance with the requirements of this AD,
and thereafter at intervals not to exceed 600 hours time-in-service:
Accomplish the requirements of paragraph (a) of this AD.
(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, Wichita Aircraft Certification
Office (ACO), FAA, Small 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, Wichita ACO.
Note 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Wichita ACO.
(f) 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.
(g) The actions shall be done in accordance with either Learjet
Service Bulletin SB 23/24/25-28-2, dated October 6, 1995; or Learjet
Service Bulletin SB 35/36-28-10, dated October 6, 1995; 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 Learjet, Inc., One
Learjet Way, Wichita, Kansas 67209-2942. Copies may be inspected at
the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW.,
Renton, Washington; or at the FAA, Wichita Aircraft Certification
Office, Small Airplane Directorate, 1801 Airport Road, Room 100,
Mid-Continent Airport, Wichita, Kansas; or at the Office of the
Federal Register, 800 North Capitol Street, NW., suite 700,
Washington, DC.
(h) This amendment becomes effective on December 27, 1995.
Issued in Renton, Washington, on November 27, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-29300 Filed 12-11-95; 8:45 am]
BILLING CODE 4910-13-U
