E9-20637. Airworthiness Directives; Learjet Model 45 Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for certain Learjet Model 45 airplanes. This proposed AD would require inspecting the baggage bay door fire barrier seal for inconel mesh in the fire barrier seal material; for certain airplanes, inspecting the fiberglass doublers for presence of red Room Temperature Vulcanizing (RTV) sealant; and doing related investigative and corrective actions if necessary. This proposed AD results from reports of incorrect external baggage door seal material and door seal sealant as well as incorrect sealant on interior baggage panels used during manufacture of the airplane. We are proposing this AD to prevent the use of door seals and sealant that do not meet flammability requirements, which could result in an uncontrollable and undetected fire within the baggage compartment.

DATES:

We must receive comments on this proposed AD by October 13, 2009.

ADDRESSES:

You may send comments by any of the following methods:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: [phone].
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Hand Delivery: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, 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; telephone [phone]; fax [phone]; e-mail [e-mail]; Internet http://www.bombardier.com. You may review copies of the referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221 or 425-227-1152.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Office (telephone [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

William Griffith, Aerospace Engineer, Airframe Branch, ACE-118W, FAA, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2009-0719; Directorate Identifier 2009-NM-078-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD because of those comments.

We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this proposed AD.

Discussion

We propose to adopt a new airworthiness directive (AD) for certain Learjet Model 45 airplanes. This proposed AD results from reports of incorrect external baggage door seal material and door seal sealant as well as incorrect sealant on interior baggage panels used during manufacture of the airplane. If a fire or heat source deteriorates the non-conforming door seal, the flow characteristics of this compartment will no longer be maintained, and the fire threat could potentially spread to the interior baggage panels. This condition, if not corrected, could result in uncontrollable and undetected fire within the baggage compartment.

Relevant Service Information

We have reviewed the service bulletins listed in the following table.

Service Bulletins

Service bulletin	Revision	Dated
Bombardier Service Bulletin 40-52-07	1	July 21, 2008.
Bombardier Service Bulletin 45-52-16	1	July 21, 2008.
Bombardier Service Bulletin 40-25-11	1	January 19, 2009.
Bombardier Service Bulletin 45-25-21	1	January 19, 2009.

Bombardier Service Bulletins 40-52-07 and 45-52-16, both Revision 1, both dated July 21, 2008, describe procedures for inspecting for the presence of inconel mesh in the baggage bay door fire barrier seal material, and doing related investigative and corrective actions as applicable. The corrective actions include replacing the fire barrier seal if inconel mesh is not present in the baggage bay door fire barrier seal. The related investigative action is inspecting for the presence of dark gray firewall sealant used to attach the fire barrier seal to the baggage bay door if inconel mesh is present in the fire barrier seal, and for airplanes on which there is no dark grey firewall sealant, the corrective action is replacing the fire barrier seal.

Bombardier Service Bulletins 40-25-11 and 45-25-21, both Revision 1, both dated January 19, 2009, describe procedures for inspecting the outer surfaces of the fiberglass doublers for presence of red Room Temperature Vulcanizing (RTV) sealant. For airplanes on which there is any red RTV sealant found, these service bulletins describe procedures for replacing the sealant with a primerless sealant.

FAA's Determination and Requirements of This Proposed AD

We are proposing this AD because we evaluated all relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design. This proposed AD would require accomplishing the actions specified in the service information described previously.

Costs of Compliance

We estimate that this proposed AD would affect 256 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Estimated Costs

Action	Work hours	Average labor rate per hour	Cost per product	Number of U.S.-registered airplanes	Fleet cost
Inspection and modification of red RTV sealant	10	$80	$800	Up to 256	Up to $204,800.
Inspection and modification of fire barrier seal	6	80	480	Up to 256	Up to $122,880.

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 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 this 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.

You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by reference
• 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.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by adding the following new AD:

Learjet: Docket No. FAA-2009-0719; Directorate Identifier 2009-NM-078-AD.

Comments Due Date

(a) We must receive comments by October 13, 2009.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Learjet Model 45 airplanes, certificated in any category, serial numbers 45-005 through 45-321 inclusive, 45-323 through 45-332 inclusive, and 45-2001 through 45-2075 inclusive.

Subject

(d) Air Transport Association (ATA) of America Code 52: Doors, and ATA Code 25: Equipment/Furnishings.

Unsafe Condition

(e) This AD results from reports of incorrect external baggage door seal material and door seal sealant, as well as incorrect sealant on interior baggage panels used during manufacture of the airplane. The Federal Aviation Administration is issuing this AD to prevent the use of door seals and sealant that do not meet flammability requirements, which could result in an uncontrollable and undetected fire within the baggage compartment.

Compliance

(f) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Inspection of Red Room Temperature Vulcanizing (RTV) Sealant in Aft Baggage Bay

(g) For airplanes having serial numbers 45-005 through 45-314 inclusive and 45-2001 through 45-2065 inclusive: Within 300 flight hours after the effective date of this AD, do a general visual inspection of the outer surfaces of the fiberglass doublers for the presence of red RTV sealant, in accordance with the Accomplishment Instructions in Bombardier Service Bulletin 45-25-21, Revision 1, dated January 19, 2009; or 40-25-11, Revision 1, dated January 19, 2009; as applicable. If any red RTV sealant is found, before further flight, replace the sealant in accordance with the Accomplishment Instructions in Bombardier Service Bulletin 45-25-21, Revision 1, dated January 19, 2009; or 40-25-11, Revision 1, dated January 19, 2009; as applicable.

Note 1:

For the purposes of this AD, a general visual inspection is: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to ensure visual access to all surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

Inspection of Baggage Bay Door Fire Barrier Seal

(h) For all airplanes: Within 300 flight hours after the effective date of this AD, do a general visual inspection of the baggage bay door fire barrier seal for the presence of metal inconel mesh in the material, and do all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions in Bombardier Service Bulletin 45-52-16, Revision 1, dated July 21, 2008; or 40-52-07, Revision 1, dated July 21, 2008; as applicable. Do all applicable related investigative and corrective actions before further flight in accordance with the Accomplishment Instructions in Bombardier Service Bulletin 45-52-16, Revision 1, dated July 21, 2008; or 40-52-07, Revision 1, dated July 21, 2008; as applicable.

Alternative Methods of Compliance (AMOCs)

(i)(1) The Manager, Wichita Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to ATTN: William Griffith, Aerospace Engineer, Airframe Branch, ACE-118W, FAA, Wichita ACO, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone [phone]; fax [phone].

(2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your principal maintenance inspector (PMI) or principal avionics inspector (PAI), as appropriate, or lacking a principal inspector, your local Flight Standards District Office. The AMOC approval letter must specifically reference this AD.

Issued in Renton, Washington, on August 18, 2009.

Stephen P. Boyd,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.