AD 2005-16-09

The FAA is superseding an existing airworthiness directive (AD), which applies to certain Learjet Model 23, 24, 25, 35, and 36 airplanes. That 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 new AD requires 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 ends the existing repetitive inspections. This AD results from 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 inthe wings of the airplane.

DATES: Effective September 13, 2005.

The Director of the Federal Register approved the incorporation by reference of Bombardier Service Bulletin SB 23/24/25-28-7, Revision 2, dated May 9, 2001; and Bombardier Service Bulletin SB 35/36-28-14, Revision 2, dated May 9, 2001; as of September 13, 2005.

On December 27, 1995 (60 FR 63617, December 12, 1995), the Director of the Federal Register approved the incorporation by reference of Learjet Service Bulletin SB 23/24/25-28-2, dated October 6, 1995; and Learjet Service Bulletin SB 35/36-28-10, dated October 6, 1995.

Final rule.

2005-16-09 Learjet: Amendment 39-14214. Docket No. FAA-2005-20798; Directorate Identifier 2004-NM-257-AD.

Effective Date

(a) This AD becomes effective September 13, 2005.

Affected ADs

(b) This AD supersedes AD 95-25-03, amendment 39-9447.

Applicability

(c) This AD applies to the airplanes in Table 1 of this AD, certificated in any category.

Table 1.--Applicability
Learjet
Serial numbers
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 results from 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 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 of This AD

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 Bombardier Service Bulletin SB 23/24/25-28-7, Revision 2, dated May 9, 2001 (for Model 23, 24, and25 airplanes); or Bombardier Service Bulletin SB 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.

Material Incorporated by Reference

(m) You must use the applicable service bulletins identified in Table 2 of this AD to perform the actions that are required by this AD, unless the AD specifies otherwise.

(1) The Director of the Federal Register approved the incorporation by reference of Bombardier Service Bulletin SB 23/24/ 25-28-7, Revision 2, dated May 9, 2001; and Bombardier Service Bulletin SB 35/36-28-14, Revision 2, dated May 9, 2001; in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.

(2) On December 27, 1995 (60 FR 63617, December 12, 1995), the Director of the Federal Register approved the incorporation by reference of Learjet Service Bulletin SB 23/24/25-28-2, dated October 6, 1995; and Learjet Service Bulletin SB 35/36-28-10, dated October 6, 1995.

(3) Contact Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942, for a copy of this service information. You may review copies at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., Room PL-401, Nassif Building, Washington, DC; on the Internet at http://dms.dot.gov; or at the National Archives and Records Administration (NARA). For information on the availability of this material at the NARA, call (202) 741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html .

TABLE 2. MATERIAL INCORPORATED BY REFERENCE
Service bulletin
Revision level
Date
Bombardier Service Bulletin SB 23/24/25 28 7 ...............
2 ...............................
May 9, 2001.
Bombardier Service Bulletin SB 35/36 28 14 .................
2 ...............................
May 9, 2001.
Learjet Service Bulletin SB 23/24/25 28 2...........................
Original ....................
October 6, 1995.
Learjet Service Bulletin SB 35/36 28 10..............................
Original ....................
October 6, 1995.

Examining the Docket

You may 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 street address stated in the ADDRESSES section.

Discussion

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that supersedes AD 95-25-03, amendment 39- 9447 (60 FR 63617, December 12, 1995). The existing AD applies to certain Learjet Model 23, 24, 25, 35, and 36 airplanes. That NPRM was published in the Federal Register on April 4, 2005 (70 FR 16984). That NPRM proposed to require repetitive inspections to detect deterioration of both flappers of the tip tank in each wing of the airplane, and various follow-on actions. That NPRM also proposed to require replacing the flappers with new flappers, and repetitively performing certain other follow-on actions. In addition, that NPRM proposed to 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 ends the existing repetitive inspections.

Comments

We provided the public the opportunity to participate in the development of this AD. No comments have been received on the NPRM or on the determination of the cost to the public.

Change to Certain Service Bulletin References

We have revised the NPRM to correct the airplane manufacturer's name from "Learjet" to "Bombardier" in the title of the following referenced service bulletins: Bombardier Service Bulletin 23/24/25-28- 7, Revision 2, dated May 9, 2001; and Bombardier Service Bulletin 35/ 36-28-14, Revision 2, dated May 9, 2001.

ConclusionWe have carefully reviewed the available data and determined that air safety and the public interest require adopting the AD with the change described previously. We have determined that this change will neither increase the economic burden on any operator nor increase the scope of the AD.

Costs of Compliance

There are about 1,459 airplanes of the affected design in the worldwide fleet. This AD will affect about 882 airplanes of U.S. registry.

The actions that are required by AD 95-25-03 and retained in this 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 actions will take about 2 work hours per airplane, at an average labor rate of $65 per work hour. Required parts will cost about $327 or $1,262 per airplane (depending on the kit installed). Based on thesefigures, the estimated cost of the new actions specified in this 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 thisrulemaking action.

Regulatory Findings

We have determined that this AD will not have federalism implications under Executive Order 13132. This AD will 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 this AD:

(1) Is not a "significant regulatory action" under Executive Order 12866;

(2) Is not a "significant rule" under 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 AD and placed it in the AD docket. 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, Incorporation by reference, Safety.

Adoption of the Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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 Federal Aviation Administration (FAA) amends Sec. 39.13 by removing amendment 39-9447 (60 FR 63617, December 12, 1995) and by adding the following new airworthiness directive (AD):