[Federal Register Volume 70, Number 71 (Thursday, April 14, 2005)]
[Proposed Rules]
[Pages 19718-19720]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-7484]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2005-20947; Directorate Identifier 2004-NM-245-AD]
RIN 2120-AA64
Airworthiness Directives; Learjet Model 23, 24, 24A, 24B, 24B-A,
24D, 24D-A, 24E, 24F, 25, 25A, 25B, 25C, 25D, and 25F Airplanes
Modified by Supplemental Type Certificate SA1731SW, SA1669SW, or
SA1670SW
AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for certain Learjet Model 23, 24, 24A, 24B, 24B-A, 24D, 24D-A, 24E,
24F, 25, 25A, 25B, 25C, 25D, and 25F airplanes. This proposed AD would
require removing the thrust reverser accumulator, and making the thrust
reverser hydraulic system and the thrust reversers inoperable. This
proposed AD is prompted by reports of the failure of two thrust
reverser accumulators. We are proposing this AD to prevent failure of
the thrust reverser accumulators, due to fatigue cracking on the female
threads, which could result in the loss of hydraulic power and damage
to the surrounding airplane structure.
DATES: We must receive comments on this proposed AD by May 31, 2005.
ADDRESSES: Use one of the following addresses to submit comments on
this proposed AD.
DOT Docket Web site: Go to http://dms.dot.gov and follow
the instructions for sending your comments electronically.
Government-wide rulemaking Web site: Go to http://
www.regulations.gov and follow the instructions for sending your
comments electronically.
Mail: Docket Management Facility, U.S. Department of
Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401,
Washington, DC 20590.
By fax: (202) 493-2251.
Hand Delivery: Room PL-401 on the plaza level of the
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
For service information identified in this proposed AD, contact The
Nordam Group, Nacelle/Thrust Reverser Systems Division, 6911 North
Whirlpool Drive, Tulsa, OK 74117.
You can examine the contents of this AD docket on the Internet at
http://dms.dot.gov, or in person at the Docket Management Facility,
U.S. Department of Transportation, 400 Seventh Street, SW., room PL-
401, on the plaza level of the Nassif Building, Washington, DC. This
docket number is FAA-2005-20947; the directorate identifier for this
docket is 2004-NM-245-AD.
FOR FURTHER INFORMATION CONTACT: Jim Rankin, Aerospace Engineer,
Special Certification Office, ASW-190, FAA, Rotorcraft Directorate,
2601 Meacham Boulevard, Fort Worth, Texas, 76137-4298; telephone (817)
222-5138; fax (817) 222-5785.
SUPPLEMENTARY INFORMATION:
Comments Invited
We invite you to submit any relevant written data, views, or
arguments regarding this proposed AD. Send your comments to an address
listed under ADDRESSES. Include ``Docket No. FAA-2005-20947;
Directorate Identifier 2004-NM-245-AD'' in the subject line of your
comments. We specifically invite comments on the overall regulatory,
economic, environmental, and energy aspects of the proposed AD. We will
consider all comments submitted by the closing date and may amend the
proposed AD in light of those comments.
We will post all comments we receive, without change, to http://
dms.dot.gov, including any personal information you provide. We will
also post a report summarizing each substantive verbal contact with FAA
personnel concerning this proposed AD. Using the search function of
that Web site, anyone can find and read the comments in any of our
dockets, including the name of the individual who sent the comment (or
signed the comment on behalf of an association, business, labor union,
etc.). You can review DOT's complete Privacy Act Statement in the
Federal Register published on April 11, 2000 (65 FR 19477-78), or you
can visit http://dms.dot.gov.
Examining the Docket
You can examine the AD docket on the Internet at http://
dms.dot.gov, or in person at the Docket Management Facility office
between 9 a.m. and 5 p.m., Monday through Friday, except Federal
holidays. The Docket Management Facility office (telephone (800) 647-
5227) is located on the plaza level of the Nassif Building at the DOT
street address stated in the ADDRESSES section. Comments will be
available in the AD docket shortly after the DMS receives them.
[[Page 19719]]
Discussion
We have received reports indicating the failure of two thrust
reverser accumulators, part number (P/N) 25-0570-127-7. One of the
failures occurred in flight during final approach of an airplane and
resulted in the loss of hydraulic power and damage to the airplane
tailcone. The other failure occurred when a repair facility was proof
testing an accumulator at 2,250 psig (the accumulator is rated for
1,500 psig). Inspection of both of these thrust reverser accumulators
found suspected fatigue cracking on the female threads where the halves
are joined. This condition, if not corrected, could result in the loss
of hydraulic power and damage to the surrounding airplane structure.
The thrust reverser accumulators having P/N 25-0570-127-1, -3, -13,
or -17 on certain Learjet Model 23, 24, 24A, 24B, 24B-A, 24D, 24D-A,
24E, 24F, 25, 25A, 25B, 25C, 25D, and 25F airplanes are identical to
those on the affected airplanes having P/N 25-0570-127-7. Therefore,
all of these models with any of these part numbers may be subject to
the same unsafe condition.
Relevant Service Information
We have reviewed The Nordam Group Alert Service Bulletin A3000 78-
21, dated November 25, 2002. The service bulletin describes procedures
for removing the thrust reverser accumulator, and making the thrust
reverser hydraulic system and the thrust reversers inoperable.
FAA's Determination and Requirements of the Proposed AD
We have evaluated all pertinent information and identified an
unsafe condition that is likely to exist or develop on other airplanes
of this same type design. Therefore, we are proposing this AD, which
would require accomplishing the actions specified in the service
information described previously, except as discussed under
``Difference Between the Proposed AD and Service Bulletin.''
Differences Between the Proposed AD and Service Bulletin
Operators should note that, although the service bulletin specifies
the compliance time as ``not later than 10 flight-hours from receipt of
this alert service bulletin,'' this proposed AD specifies a compliance
time of ``within 60 days after the effective date of this AD.'' In
developing an appropriate compliance time for this AD, the FAA
considered not only the manufacturer's recommendation, but the degree
of urgency associated with addressing the subject unsafe condition, the
average utilization of the affected fleet, and the time necessary to
perform the actions required by the proposed AD. In light of all of
these factors, the FAA finds a compliance time of 60 days for
completing the required actions to be warranted, in that it represents
an appropriate interval of time for affected airplanes to continue to
operate without compromising safety. This difference has been
coordinated with the manufacturer.
Operators should note that, although the Accomplishment
Instructions of the referenced service bulletin describe procedures for
submitting a comment sheet recording compliance with the service
bulletin, this proposed AD would not require that action. We do not
need this information from operators.
Interim Action
This is considered to be interim action. The manufacturer has
advised that it currently is developing a modification that will
address the unsafe condition addressed by this proposed AD. Once this
modification is developed, approved, and available, we may consider
additional rulemaking.
Costs of Compliance
There are about 321 airplanes of the affected design in the
worldwide fleet. This proposed AD would affect about 255 airplanes of
U.S. registry. The proposed actions would take about 2 work hours per
airplane, at an average labor rate of $65 per work hour. Based on these
figures, the estimated cost of the proposed AD for U.S. operators is
$33,150, or $130 per airplane.
Authority for this Rulemaking
Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. Subtitle VII, Aviation Programs,
describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in
subtitle VII, part A, subpart III, section 44701, ``General
requirements.'' Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on products identified in this
rulemaking action.
Regulatory Findings
We have determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD would not
have a substantial direct effect 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.
For the reasons discussed above, I certify that the 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. 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.
We prepared a regulatory evaluation of the estimated costs to
comply with this proposed AD. See the ADDRESSES section for a location
to examine the regulatory evaluation.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
The Proposed Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 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. The FAA amends Sec. 39.13 by adding the following new
airworthiness directive (AD):
Learjet: Docket No. FAA-2005-20947; Directorate Identifier 2004-NM-
245-AD.
Comments Due Date
(a) The Federal Aviation Administration (FAA) must receive
comments on this AD action by May 31, 2005.
Affected ADs
(b) None.
Applicability
(c) This AD applies to Learjet Model 23, 24, 24A, 24B, 24B-A,
24D, 24D-A, 24E, 24F, 25, 25A, 25B, 25C, 25D, and 25F airplanes;
certificated in any category; modified by Supplemental Type
Certificate SA1731SW, SA1669SW, or SA1670SW; equipped with Nordam
(formerly Dee Howard Company) thrust reversers having part number
(P/N) 25-0570-127-1, -3, -7, -13, or -17.
[[Page 19720]]
Unsafe Condition
(d) This AD was prompted by reports of the failure of two thrust
reverser accumulators. We are issuing this AD to prevent failure of
the thrust reverser accumulators, due to fatigue cracking on the
female threads, which could result in the loss of hydraulic power
and damage to the surrounding airplane structure.
Compliance
(e) You are responsible for having the actions required by this
AD performed within the compliance times specified, unless the
actions have already been done.
Remove Thrust Reverser Accumulator
(f) Within 60 days after the effective date of this AD, remove
the thrust reverser accumulator, and make the thrust reverser
hydraulic system and the thrust reversers inoperable, by doing all
of the actions specified in the Accomplishment Instructions of The
Nordam Group Alert Service Bulletin A3000 78-21, dated November 25,
2002. Where there are differences between the Master Minimum
Equipment List and the AD, the AD prevails. Although the service
bulletin referenced in this AD specifies to submit certain
information to the manufacturer, this AD does not include that
requirement.
Parts Installation
(g) As of the effective date of this AD, no person may install a
thrust reverser accumulator having P/N 25-0570-127-1, -3, -7, -13,
or -17 on any airplane.
Alternative Methods of Compliance (AMOCs)
(h) The Manager, Special Certification Office, Rotorcraft
Directorate, FAA, has the authority to approve AMOCs for this AD, if
requested in accordance with the procedures found in 14 CFR 39.19.
Issued in Renton, Washington, on April 5, 2005.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 05-7484 Filed 4-13-05; 8:45 am]
BILLING CODE 4910-13-P