Airworthiness Directives; Learjet Model 23, 24, 25, 35, and 36 Airplanes, 16984-16986 [05-6579]
Download as PDF
16984
Federal Register / Vol. 70, No. 63 / Monday, April 4, 2005 / Proposed Rules
Issued in Renton, Washington, on March
23, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate,
Aircraft Certification Service.
[FR Doc. 05–6578 Filed 4–1–05; 8:45 am]
BILLING CODE 4910–13–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA–2005–20798; Directorate
Identifier 2004–NM–257–AD]
RIN 2120–AA64
Airworthiness Directives; Learjet
Model 23, 24, 25, 35, and 36 Airplanes
Federal Aviation
Administration (FAA), Department of
Transportation (DOT).
ACTION: Notice of proposed rulemaking
(NPRM).
AGENCY:
SUMMARY: The FAA proposes to
supersede an existing airworthiness
directive (AD) that applies to certain
Learjet Model 23, 24, 25, 35, and 36
airplanes. The existing AD currently
requires repetitive inspections to detect
deterioration of both flappers of the tip
tank in each wing of the airplane, and
various follow-on actions. The existing
AD also requires replacing the flappers
with new flappers, and repetitively
performing certain other follow-on
actions. This proposed AD would
require an inspection of the flappers and
flapper assemblies of the tip tank in
each wing or a review of the airplane
maintenance records to determine the
part numbers, and replacement of
certain flappers or flapper assemblies if
necessary, which would end the
existing repetitive inspections. This
proposed AD is prompted by the results
of numerous continual inspections, and
the approval of a new, improved flapper
and flapper assembly. We are proposing
this AD 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: We must receive comments on
this proposed AD by May 19, 2005.
ADDRESSES: Use one of the following
addresses to submit comments on this
proposed AD.
• DOT Docket Web site: Go to
https://dms.dot.gov and follow the
instructions for sending your comments
electronically.
• Government-wide rulemaking Web
site: Go to https://www.regulations.gov
and follow the instructions for sending
your comments electronically.
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15:01 Apr 01, 2005
Jkt 205001
• Mail: Docket Management Facility;
U.S. Department of Transportation, 400
Seventh Street, SW., Nassif Building,
room PL–401, Washington, DC 20590.
• 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 Learjet, Inc.,
One Learjet Way, Wichita, Kansas
67209–2942.
You can examine the contents of this
AD docket on the Internet at https://
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–
20798; the directorate identifier for this
docket is 2004–NM–257–AD.
FOR FURTHER INFORMATION CONTACT:
Jeffrey Janusz, Aerospace Engineer,
Systems and Propulsion Branch, ACE–
116W, FAA, Wichita Aircraft
Certification Office, 1801 Airport Road,
Room 100, Mid-Continent Airport,
Wichita, Kansas 67209; telephone (316)
946–4148; fax (316) 946–4107.
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–
2005–20798; Directorate Identifier
2004–NM–257–AD’’ at the beginning 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 received 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 https://
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 our docket
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 the DOT’s complete Privacy Act
Statement in the Federal Register
published on April 11, 2000 (65 FR
19477–78), or you can visit https://
dms.dot.gov.
PO 00000
Frm 00018
Fmt 4702
Sfmt 4702
Examining the Docket
You can examine the AD docket on
the Internet at https://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.
Discussion
On November 27, 1995, we issued AD
95–25–03, amendment 39–9447 (60 FR
63617, December 12, 1995), for certain
Learjet Model 23, 24, 25, 35, and 36
airplanes. That AD requires repetitive
inspections to detect deterioration of
both flappers of the tip tank in each
wing of the airplane, and various
follow-on actions. That AD also requires
replacing the flappers with new
flappers, and repetitively performing
certain other follow-on actions. That AD
was prompted by reports of imbalance
of the fuel loads in the wings of the
airplane due to failed or cracked
flappers. We issued that AD to prevent
significant reduction in the lateral
control of the airplane due to imbalance
of the fuel loads in the wings of the
airplane.
Actions Since Existing AD Was Issued
Since we issued AD 95–25–03, we
have reviewed Learjet Service Bulletin
23/24/25–28–7, Revision 2, dated May
9, 2001 (for Model 23, 24, and 25
airplanes); and Learjet Service Bulletin
35/36–28–14, Revision 2, dated May 9,
2001 (for Model 35 and 36 airplanes).
The service bulletins describe
procedures for replacing flappers with
new flappers or replacing the flapper
assemblies with new or modified and
reidentified assemblies, which
eliminates the need for the repetitive
inspections required by AD 95–25–03.
Accomplishing the actions specified in
the service information is intended to
adequately address the unsafe
condition.
FAA’s Determination and Requirements
of the Proposed AD
The unsafe condition described
previously is likely to exist or develop
on other airplanes of the same type
design that may be registered in the U.S.
at some time in the future.
We can better ensure long-term
continued operational safety by design
changes to remove the source of the
problem, rather than by repetitive
inspections. Long-term inspections, as
E:\FR\FM\04APP1.SGM
04APP1
16985
Federal Register / Vol. 70, No. 63 / Monday, April 4, 2005 / Proposed Rules
required by AD 95–25–03, may not
provide the degree of safety necessary
for the transport airplane fleet. This
determination, along with a better
understanding of the human factors and
other systems effects associated with
numerous continual inspections, has led
us to consider placing less emphasis on
inspections and more emphasis on
design improvements. The proposed
replacement requirement is consistent
with these conditions.
We are proposing to supersede AD
95–25–03. This proposed AD would
retain the requirements of the existing
AD. This proposed AD would also
require accomplishing the actions
specified in service bulletins described
previously in this proposed AD, which
would end the repetitive inspection
requirements of the existing AD. This
proposed AD would also require an
inspection of the flappers and flapper
assemblies of the tip tank in each wing,
or a review of the airplane maintenance
records, to determine the part numbers.
Change to Existing AD
This proposed AD would retain all
requirements of AD 95–25–03. Since AD
95–25–03 was issued, the AD format has
been revised, and certain paragraphs
have been rearranged. As a result, the
corresponding paragraph identifiers
have changed in this proposed AD, as
listed in the following table:
REVISED PARAGRAPH IDENTIFIERS
Requirements in
AD 95–25–03
Paragraph
Paragraph
Paragraph
Paragraph
(a)
(b)
(c)
(d)
......................
......................
......................
......................
Corresponding
requirement in
this proposed
AD
Paragraph
Paragraph
Paragraph
Paragraph
(f).
(g).
(h).
(i).
Costs of Compliance
There are about 1,459 airplanes of the
affected design in the worldwide fleet.
This proposed AD would affect about
882 airplanes of U.S. registry.
The actions that are required by AD
95–25–03 and retained in this proposed
AD take about 16 work hours per
airplane, at an average labor rate of $65
per work hour. Required parts cost
about $708 per airplane. Based on these
figures, the estimated cost of the
currently required actions is $1,541,736,
or $1,748 per airplane.
The new proposed actions would take
about 2 work hours per airplane, at an
average labor rate of $65 per work hour.
Required parts would cost about $327 or
$1,262 per airplane (depending on the
kit installed). Based on these figures, the
estimated cost of the new actions
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15:01 Apr 01, 2005
Jkt 205001
specified in this proposed AD for U.S.
operators is $457 or $1,392, per airplane
(depending on the kit installed).
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.
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.
§ 39.13
Learjet: Docket No. FAA–2005–20798;
Directorate Identifier 2004–NM–257–AD.
Comments Due Date
(a) The Federal Aviation Administration
must receive comments on this AD action by
May 19, 2005.
Affected ADs
(b) This AD supersedes AD 95–25–03,
amendment 39–9447 (60 FR 63617,
December 12, 1995).
Applicability
(c) This AD applies to the airplanes in
Table 1 of this AD, certificated in any
category.
Regulatory Findings
TABLE 1.—APPLICABILITY
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:
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Fmt 4702
Sfmt 4702
[Amended]
2. The FAA amends § 39.13 by
removing amendment 39–9447 (60 FR
63617, December 12, 1995) and adding
the following new airworthiness
directive (AD):
Learjet—
Serial Nos.
Model 23 airplanes .......
23–003 through
23–090 inclusive.
24–100 through
24–357 inclusive.
25–002 through
25–373 inclusive.
35–002 through
35–676 inclusive.
36–002 through
36–063 inclusive.
Model 24 airplanes .......
Model 25 airplanes .......
Model 35 airplanes .......
Model 36 airplanes .......
Unsafe Condition
(d) This AD was prompted by the results
of numerous continual inspections, and the
approval of a new, improved flapper and
flapper assembly. We are issuing this AD to
prevent significant reduction in the lateral
control of the airplane due to imbalance of
the fuel loads in the wings of the airplane.
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.
Requirements of AD 95–25–03
Repetitive Inspections, Related Investigative
Actions, and Replacement
(f) Within 50 hours time-in-service after
December 27, 1995 (the effective date of AD
95–25–03), 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 flappers of the tip tank in
each wing, in accordance with either Learjet
Service Bulletin SB 23/24/25–28–2, dated
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04APP1
16986
Federal Register / Vol. 70, No. 63 / Monday, April 4, 2005 / Proposed Rules
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.
(g) Except as provided in paragraph (h) of
this AD, at the later of the times specified in
paragraphs (g)(1) and (g)(2) of this AD:
Replace both flappers of the tip tank in each
wing with new flappers 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-inservice on the flapper valve, whichever
occurs earlier.
(2) Within 50 hours time-in-service after
December 27, 1995.
(h) For airplanes on which the age and
time-in-service of the flapper valve cannot be
determined: Within 50 hours time-in-service
after December 27, 1995, replace both
flappers 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.
(i) 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 (f) of this AD.
flappers and flapper assemblies can be
conclusively determined from that review.
(1) If four flappers having P/N 2323006–
802 and four flapper assemblies having P/N
2323006–801 are found installed, no further
action is required by this paragraph, and the
repetitive inspections required by paragraphs
(f) and (i) of this AD can be stopped.
(2) If any flapper having P/N 2323006–5 or
any flapper assembly having P/N 2323006–6
is found installed, within 600 hours time-inservice since last replacement of any flapper
valve in accordance with the requirements of
this AD, replace the flapper valve with a new
flapper valve or replace the flapper assembly
with new or modified and reidentified
assembly, as applicable. The replacement
must be done in accordance with the
Accomplishment Instructions of Learjet
Service Bulletin 23/24/25–28–7, Revision 2,
dated May 9, 2001 (for Model 23, 24, and 25
airplanes); or Learjet Service Bulletin 35/36–
28–14, Revision 2, dated May 9, 2001 (for
Model 35 and 36 airplanes); as applicable.
Accomplishment of the replacement ends the
repetitive inspections required by paragraphs
(f) and (i) of this AD.
Parts Installation
(k) As of the effective date of this AD, no
person may install a flapper having P/N
2323006–5 or a flapper assembly having P/
N 2323006–6, on any airplane.
Alternative Methods of Compliance (AMOCs)
(l)(1) The Manager, Wichita Aircraft
Certification Office, FAA, has the authority to
approve AMOCs for this AD, if requested in
accordance with the procedures found in 14
CFR 39.19.
(2) AMOCs approved previously according
to AD 95–25–03 are not approved as AMOCs
with this AD.
Issued in Renton, Washington, on March
22, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate,
Aircraft Certification Service.
[FR Doc. 05–6579 Filed 4–1–05; 8:45 am]
BILLING CODE 4910–13–P
New Requirements
Inspection and Replacement
(j) Within 600 hours time-in-service since
last replacement of any flapper valve in
accordance with the requirements of this AD,
or within 90 days after the effective date of
this AD, whichever occurs later, inspect the
flappers and flapper assemblies of the tip
tank in each wing to determine their part
numbers (P/N). The raised letter and
numbers ‘‘S–461’’ on the convex side of the
flappers can identify these parts. Instead of
inspecting the flappers and flapper
assemblies, a review of airplane maintenance
records is acceptable if the P/N of the
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15:01 Apr 01, 2005
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA–2005–20836; Directorate
Identifier 2005–NM–028–AD]
RIN 2120–AA64
Airworthiness Directives; Boeing
Model 727–200 and 727–200F Series
Airplanes; 737–200, 737–200C, 737–
300, and 737–400 Series Airplanes;
747–100, 747–100B, 747–100B SUD,
747–200B, 747–200C, 747–200F, 747–
300, 747–400, 747SR, and 747SP Series
Airplanes; 757–200 and 757–200PF
Series Airplanes; and 767–200 and
767–300 Series Airplanes
Federal Aviation
Administration (FAA), Department of
Transportation (DOT).
ACTION: Notice of proposed rulemaking
(NPRM).
AGENCY:
SUMMARY: The FAA proposes to adopt a
new airworthiness directive (AD) for
certain Boeing transport category
airplanes. This proposed AD would
require replacing any insulation
blanket constructed of
polyethyleneteraphthalate (PET) film,
ORCON Orcofilm AN–26 (hereafter
‘‘AN–26’’) with a new insulation
blanket. This proposed AD is prompted
by reports of in-flight and ground fires
on certain airplanes manufactured with
insulation blankets covered with AN–
26, which may contribute to the spread
of a fire when ignition occurs from
sources such as electrical arcing or
sparking. We are proposing this AD to
ensure that insulation blankets
constructed of AN–26 are removed from
the fuselage. Such insulation blankets
could propagate a fire that is the result
of electrical arcing or sparking.
EFFECTIVE DATES: We must receive
comments on this proposed AD by June
3, 2005.
ADDRESSES: Use one of the following
addresses to submit comments on this
proposed AD.
• DOT Docket Web site: Go to
https://dms.dot.gov and follow the
instructions for sending your comments
electronically.
• Government-wide rulemaking Web
site: Go to https://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,
E:\FR\FM\04APP1.SGM
04APP1
Agencies
[Federal Register Volume 70, Number 63 (Monday, April 4, 2005)]
[Proposed Rules]
[Pages 16984-16986]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-6579]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2005-20798; Directorate Identifier 2004-NM-257-AD]
RIN 2120-AA64
Airworthiness Directives; Learjet Model 23, 24, 25, 35, and 36
Airplanes
AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: The FAA proposes to supersede an existing airworthiness
directive (AD) that applies to certain Learjet Model 23, 24, 25, 35,
and 36 airplanes. The existing AD currently requires repetitive
inspections to detect deterioration of both flappers of the tip tank in
each wing of the airplane, and various follow-on actions. The existing
AD also requires replacing the flappers with new flappers, and
repetitively performing certain other follow-on actions. This proposed
AD would require an inspection of the flappers and flapper assemblies
of the tip tank in each wing or a review of the airplane maintenance
records to determine the part numbers, and replacement of certain
flappers or flapper assemblies if necessary, which would end the
existing repetitive inspections. This proposed AD is prompted by the
results of numerous continual inspections, and the approval of a new,
improved flapper and flapper assembly. We are proposing this AD 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: We must receive comments on this proposed AD by May 19, 2005.
ADDRESSES: Use one of the following addresses to submit comments on
this proposed AD.
DOT Docket Web site: Go to https://dms.dot.gov and follow
the instructions for sending your comments electronically.
Government-wide rulemaking Web site: Go to https://
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.
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
Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942.
You can examine the contents of this AD docket on the Internet at
https://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-2005-20798; the directorate identifier for this
docket is 2004-NM-257-AD.
FOR FURTHER INFORMATION CONTACT: Jeffrey Janusz, Aerospace Engineer,
Systems and Propulsion Branch, ACE-116W, FAA, Wichita Aircraft
Certification Office, 1801 Airport Road, Room 100, Mid-Continent
Airport, Wichita, Kansas 67209; telephone (316) 946-4148; fax (316)
946-4107.
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-2005-20798;
Directorate Identifier 2004-NM-257-AD'' at the beginning 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 received 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 https://
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 our
docket 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 the DOT's complete Privacy Act Statement in the
Federal Register published on April 11, 2000 (65 FR 19477-78), or you
can visit https://dms.dot.gov.
Examining the Docket
You can examine the AD docket on the Internet at https://
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.
Discussion
On November 27, 1995, we issued AD 95-25-03, amendment 39-9447 (60
FR 63617, December 12, 1995), for certain Learjet Model 23, 24, 25, 35,
and 36 airplanes. That AD requires repetitive inspections to detect
deterioration of both flappers of the tip tank in each wing of the
airplane, and various follow-on actions. That AD also requires
replacing the flappers with new flappers, and repetitively performing
certain other follow-on actions. That AD was prompted by reports of
imbalance of the fuel loads in the wings of the airplane due to failed
or cracked flappers. We issued that AD to prevent significant reduction
in the lateral control of the airplane due to imbalance of the fuel
loads in the wings of the airplane.
Actions Since Existing AD Was Issued
Since we issued AD 95-25-03, we have reviewed Learjet Service
Bulletin 23/24/25-28-7, Revision 2, dated May 9, 2001 (for Model 23,
24, and 25 airplanes); and Learjet Service Bulletin 35/36-28-14,
Revision 2, dated May 9, 2001 (for Model 35 and 36 airplanes). The
service bulletins describe procedures for replacing flappers with new
flappers or replacing the flapper assemblies with new or modified and
reidentified assemblies, which eliminates the need for the repetitive
inspections required by AD 95-25-03. Accomplishing the actions
specified in the service information is intended to adequately address
the unsafe condition.
FAA's Determination and Requirements of the Proposed AD
The unsafe condition described previously is likely to exist or
develop on other airplanes of the same type design that may be
registered in the U.S. at some time in the future.
We can better ensure long-term continued operational safety by
design changes to remove the source of the problem, rather than by
repetitive inspections. Long-term inspections, as
[[Page 16985]]
required by AD 95-25-03, may not provide the degree of safety necessary
for the transport airplane fleet. This determination, along with a
better understanding of the human factors and other systems effects
associated with numerous continual inspections, has led us to consider
placing less emphasis on inspections and more emphasis on design
improvements. The proposed replacement requirement is consistent with
these conditions.
We are proposing to supersede AD 95-25-03. This proposed AD would
retain the requirements of the existing AD. This proposed AD would also
require accomplishing the actions specified in service bulletins
described previously in this proposed AD, which would end the
repetitive inspection requirements of the existing AD. This proposed AD
would also require an inspection of the flappers and flapper assemblies
of the tip tank in each wing, or a review of the airplane maintenance
records, to determine the part numbers.
Change to Existing AD
This proposed AD would retain all requirements of AD 95-25-03.
Since AD 95-25-03 was issued, the AD format has been revised, and
certain paragraphs have been rearranged. As a result, the corresponding
paragraph identifiers have changed in this proposed AD, as listed in
the following table:
Revised Paragraph Identifiers
------------------------------------------------------------------------
Corresponding requirement in
Requirements in AD 95-25-03 this proposed AD
------------------------------------------------------------------------
Paragraph (a)........................... Paragraph (f).
Paragraph (b)........................... Paragraph (g).
Paragraph (c)........................... Paragraph (h).
Paragraph (d)........................... Paragraph (i).
------------------------------------------------------------------------
Costs of Compliance
There are about 1,459 airplanes of the affected design in the
worldwide fleet. This proposed AD would affect about 882 airplanes of
U.S. registry.
The actions that are required by AD 95-25-03 and retained in this
proposed AD take about 16 work hours per airplane, at an average labor
rate of $65 per work hour. Required parts cost about $708 per airplane.
Based on these figures, the estimated cost of the currently required
actions is $1,541,736, or $1,748 per airplane.
The new proposed actions would take about 2 work hours per
airplane, at an average labor rate of $65 per work hour. Required parts
would cost about $327 or $1,262 per airplane (depending on the kit
installed). Based on these figures, the estimated cost of the new
actions specified in this proposed AD for U.S. operators is $457 or
$1,392, per airplane (depending on the kit installed).
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 removing amendment 39-9447 (60 FR
63617, December 12, 1995) and adding the following new airworthiness
directive (AD):
Learjet: Docket No. FAA-2005-20798; Directorate Identifier 2004-NM-
257-AD.
Comments Due Date
(a) The Federal Aviation Administration must receive comments on
this AD action by May 19, 2005.
Affected ADs
(b) This AD supersedes AD 95-25-03, amendment 39-9447 (60 FR
63617, December 12, 1995).
Applicability
(c) This AD applies to the airplanes in Table 1 of this AD,
certificated in any category.
Table 1.--Applicability
------------------------------------------------------------------------
Learjet-- Serial Nos.
------------------------------------------------------------------------
Model 23 airplanes........................ 23-003 through 23-090
inclusive.
Model 24 airplanes........................ 24-100 through 24-357
inclusive.
Model 25 airplanes........................ 25-002 through 25-373
inclusive.
Model 35 airplanes........................ 35-002 through 35-676
inclusive.
Model 36 airplanes........................ 36-002 through 36-063
inclusive.
------------------------------------------------------------------------
Unsafe Condition
(d) This AD was prompted by the results of numerous continual
inspections, and the approval of a new, improved flapper and flapper
assembly. We are issuing this AD to prevent significant reduction in
the lateral control of the airplane due to imbalance of the fuel
loads in the wings of the airplane.
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.
Requirements of AD 95-25-03
Repetitive Inspections, Related Investigative Actions, and
Replacement
(f) Within 50 hours time-in-service after December 27, 1995 (the
effective date of AD 95-25-03), 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 flappers of the tip tank in each wing, in accordance with
either Learjet Service Bulletin SB 23/24/25-28-2, dated
[[Page 16986]]
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.
(g) Except as provided in paragraph (h) of this AD, at the later
of the times specified in paragraphs (g)(1) and (g)(2) of this AD:
Replace both flappers of the tip tank in each wing with new flappers
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 December 27, 1995.
(h) For airplanes on which the age and time-in-service of the
flapper valve cannot be determined: Within 50 hours time-in-service
after December 27, 1995, replace both flappers 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.
(i) 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 (f) of this AD.
New Requirements
Inspection and Replacement
(j) Within 600 hours time-in-service since last replacement of
any flapper valve in accordance with the requirements of this AD, or
within 90 days after the effective date of this AD, whichever occurs
later, inspect the flappers and flapper assemblies of the tip tank
in each wing to determine their part numbers (P/N). The raised
letter and numbers ``S-461'' on the convex side of the flappers can
identify these parts. Instead of inspecting the flappers and flapper
assemblies, a review of airplane maintenance records is acceptable
if the P/N of the flappers and flapper assemblies can be
conclusively determined from that review.
(1) If four flappers having P/N 2323006-802 and four flapper
assemblies having P/N 2323006-801 are found installed, no further
action is required by this paragraph, and the repetitive inspections
required by paragraphs (f) and (i) of this AD can be stopped.
(2) If any flapper having P/N 2323006-5 or any flapper assembly
having P/N 2323006-6 is found installed, within 600 hours time-in-
service since last replacement of any flapper valve in accordance
with the requirements of this AD, replace the flapper valve with a
new flapper valve or replace the flapper assembly with new or
modified and reidentified assembly, as applicable. The replacement
must be done in accordance with the Accomplishment Instructions of
Learjet Service Bulletin 23/24/25-28-7, Revision 2, dated May 9,
2001 (for Model 23, 24, and 25 airplanes); or Learjet Service
Bulletin 35/36-28-14, Revision 2, dated May 9, 2001 (for Model 35
and 36 airplanes); as applicable. Accomplishment of the replacement
ends the repetitive inspections required by paragraphs (f) and (i)
of this AD.
Parts Installation
(k) As of the effective date of this AD, no person may install a
flapper having P/N 2323006-5 or a flapper assembly having P/N
2323006-6, on any airplane.
Alternative Methods of Compliance (AMOCs)
(l)(1) The Manager, Wichita Aircraft Certification Office, FAA,
has the authority to approve AMOCs for this AD, if requested in
accordance with the procedures found in 14 CFR 39.19.
(2) AMOCs approved previously according to AD 95-25-03 are not
approved as AMOCs with this AD.
Issued in Renton, Washington, on March 22, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 05-6579 Filed 4-1-05; 8:45 am]
BILLING CODE 4910-13-P