AD 2009-21-10

This AD is effective December 17, 2009.

We must receive comments on this AD by January 19, 2010.

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: 202-493-2251.

• 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.

Robert Hettman, Aerospace Engineer, Cabin Safety and Environmental Systems Branch, ANM-150S, Seattle Aircraft Certification Office, FAA, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6457; fax (425) 917-6590.

During routine hydrostatic testing, a United States Department of Transportation Type 3HT-1850 high-pressure gaseous oxygen cylinder ruptured under what would be considered normal operating conditions. Further investigation indicates that the cylinder had insufficient strength characteristics due to improper heat treatment. The improper heat treatment is limited to specific production batches, but the affected oxygen cylinders may be installed on various transport airplanes and aircraft certificated in other categories. The oxygen cylinders contain gaseous oxygen under high pressure. Rupture of an oxygen cylinder, depending on its location, could result in structural damage and rapid decompression of the airplane, damage to adjacent essential flight equipment, deprivation of the necessary oxygen supply for the flightcrew, and injury to cabin occupants or maintenance or other support personnel.

Certain affected airplanes have been approved by the aviation authorities of other countries, and are approved for operation in the United States.

We are issuing this AD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of these same type designs. This AD requires removing the affected oxygen cylinder assemblies from transport airplanes.

The FAA is currently evaluating the risk associated with these oxygen cylinder assemblies installed on aircraft certificated in other categories to determine whether any action is necessary to address the unsafe condition on these aircraft.

This AD addresses the consequences of the potential rupture of certain oxygen cylinder assemblies. Because of our requirement to promote safe flight of civil aircraft and thus the critical need to ensure the proper functioning of the oxygen cylinders and the short compliance time involved with this action, this AD must be issued immediately.

Because an unsafe condition exists that requires the immediate adoption of this AD, we find notice and opportunity for prior public comment hereon are impracticable and that good cause exists for making this amendment effective in less than 30 days.

This AD is a final rule that involves requirements affecting flight safety, and we did not provide you with notice and an opportunity to provide your comments before it becomes effective. However, we invite you to send any written data, views, or arguments about this AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2009-0915; Directorate Identifier 2009-NM-224-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this AD. We will consider all comments received by the closing date and may amend this 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 AD.

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.

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.

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

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 FAA amends § 39.13 by adding the following new AD: