AD 2007-04-18

This AD becomes effective March 23, 2007.

The Director of the Federal Register approved the incorporation by reference of certain publications listed in the AD as of March 23, 2007.

You may examine the 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., Nassif Building, Room PL-401, Washington, DC.

Contact Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942, for service information identified in this AD.

James Galstad, Aerospace Engineer, Mechanical Systems and Propulsion Branch, ACE-116W, FAA, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316) 946-4135; fax (316) 946-4107.

You may examine the airworthiness directive (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.

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to certain Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F, 28, 29, 31, 31A, 35, 35A (C-21A), 36, 36A, 55, 55B, and 55C airplanes. That NPRM was published in the Federal Register on August 16, 2006 (71 FR 47154). That NPRM proposed to require modifying the left- and right-hand standby fuel pump switches. That NPRM also proposed to require revising the Emergency and Abnormal Procedures sections of the airplane flight manual (AFM) to advise the flightcrew of the proper procedures to follow in the event of failure of the standby fuel pump to shut off.

We provided the public the opportunity to participate in the development of this AD. We have considered the comments received.

One private citizen states that the flight department he works for operates three Learjet Model 35A airplanes and a Learjet Model 31 airplane. He adds that the airplanes have never had an inadvertent operation of the fuel pumps resulting in an over-limit fuel imbalance. He also notes that the fuel crossflow valve must be open in order to transfer fuel; this requires two switches to be selected—the standby fuel pump and the crossflow valve. He states that even if a standby fuel pump is inadvertently activated, no fuel will be transferred unless the crossflow valve is also open. He concludes that there is already enough protection in the system to avoid an over-limit fuel imbalance.

We infer that the commenter is stating that an AD is not required. We recognize that the crossflow valve must be open for fuel to be transferred; however, as the operation of the pump may not be recognized by the flightcrew, the transfer valve may be opened in an attempt to correct an existing fuel imbalance, creating an even greater imbalance. We do not agree that there is enough protection in the system to avoid an over-limit fuel imbalance when an electrical malfunction provides power to an electric standby pump. This condition was found during an accident investigation. We have made no change to the AD in this regard.

Another private citizen states that his organization has operated up to 13 Learjet 20 series airplanes (some with 20,000 total airframe hours) for almost 20 years and has never encountered the unsafe condition. He adds that if this problem were to occur, it should not generate an emergency situation but simply an abnormal procedure that is addressed by the aircraft checklist. He asks what pertinent information leads to the conclusion that an unsafe condition is likely to exist or develop on other airplanes. He adds that the condition of imbalance caused by inadvertent standby pump operation, as specified in the NPRM, is not likely to occur; if it did occur, the flightcrew could read the proper procedure in the checklist. He concludes that safety is not jeopardized at all.

We infer that the commenter wants us to withdraw the NPRM; we do not agree with the request. We acknowledge that existing airplane checklist procedures appear to be adequate, but using previous AFM procedures does not ensure that the imbalance will be corrected. Based on the data presented to date of over 30 reports of imbalance, we find that this AD is warranted. We have made no change to the AD in this regard.

The Modification and Replacement Parts Association (MARPA) states that ADs are based on service information that originates from the type certificate holder or its suppliers. MARPA adds that manufacturer's service documents are privately authored instruments, generally having copyright protection against duplication and distribution. When a service document is incorporated by reference into a public document, such as an AD, pursuant to 5 U.S.C. 552(a) and 1 CFR part 51, it loses its private, protected status and becomes a public document. MARPA notes that if a service document is used as a mandatory element of compliance, it should not simply be referenced, but should be incorporated by reference. MARPA believes that public laws, by definition, should be public, which means they cannot rely upon private writings for compliance. MARPA adds that the legal interpretation of a document is a question of law, not of fact; therefore, unless the service document is incorporated by reference it cannot be considered. MARPA is concerned that failure to incorporate essential service information could result in a court decision invalidating the AD.

MARPA also states that service documents incorporated by reference should be made available to the public by publication in the Docket Management System (DMS), keyed to the action that incorporates those documents. MARPA notes that the stated purpose of the incorporation by reference method is brevity, to keep from expanding the Federal Register needlessly by publishing documents already in the hands of the affected individuals. MARPA adds that, traditionally, “affected individuals” means aircraft owners and operators, who are generally provided service information by the manufacturer. MARPA adds that a new class of affected individuals has emerged, since the majority of aircraft maintenance is now performed by specialty shops instead of aircraft owners and operators. MARPA notes that this new class includes maintenance and repair organizations, component servicing, and/or servicing alternatively certified parts under section 21.303 (“Replacement and modification parts”) of the Federal Aviation Regulations (14 CFR 21.303). MARPA notes that distribution to owners may, when the owner is a financing or leasing institution, not actually reach the people responsible for accomplishing the AD. Therefore, MARPA asks that the service documents deemed essential to the accomplishment of the NPRM be incorporated by reference into the regulatory instrument and published in DMS.

We acknowledge MARPA's comments. The Office of the Federal Register (OFR) requires that documents that are necessary to accomplish the requirements of the AD be incorporated by reference during the final rule phase of rulemaking. This final rule incorporates by reference the documents necessary for the accomplishment of the requirements mandated by this AD. Further, we point out that while documents that are incorporated by reference do become public information, as noted by the commenter, they do not lose their copyright protection. For that reason, we advise the public to contact the manufacturer to obtain copies of the referenced service information.

In regard to MARPA's request to post service bulletins on the Department of Transportation's DMS, we are currently in the process of reviewing issues surrounding the posting of service bulletins on the DMS as part of an AD docket. Once we have thoroughly examined all aspects of this issue and have made a final determination, we will consider whether our current practice needs to be revised. No change to the AD is necessary in response to these comments.

We have carefully reviewed the available data, including the comments received, and determined that air safety and the public interest require adopting the AD as proposed.

There are about 1,613 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this AD, at an average labor rate of $80 per work hour, depending on airplane configuration.

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.

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.

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:

1. The authority citation for part 39 continues to read as follows:

2. The Federal Aviation Administration (FAA) amends § 39.13 by adding the following new airworthiness directive (AD):