Discussion
We have received a report indicating that the main landing gear (MLG) casings have improper hydrogen embrittlement relief on certain Hawker Beechcraft Corporation Model BAe.125 series 800A (including C- 29A and U-125) airplanes, and Hawker Beechcraft Model Hawker 800XP airplanes. Certain MLG casings did not receive proper hydrogen embrittlement relief during production. Improper hydrogen embrittlement relief, if not corrected, could result in a fracture of the MLG casings and a collapse of the affected MLG, which could adversely affect the airplane's continued safe flight and landing.
Relevant Service Information
We have reviewed Hawker Beechcraft Mandatory Service Bulletin SB 32-3920, dated August 2008. The service bulletin describes procedures for doing an inspection to determine the serial number and part number on the MLG assembly, and replacing the MLG assembly with a serviceable MLG assembly if necessary. The service bulletin also specifies to contact the manufacturer to report if any affected serial number is found, return spare parts to the manufacturer and report accomplishment of the service bulletin.
FAA's Determination and Requirements of This AD
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 the same type design. This AD requires accomplishing the actions specified in the service information described previously, except as discussed under ``Differences Between the Service Bulletin and This AD.''
Differences Between the Service Bulletin and This AD
Although paragraph 1.D., ``Compliance'' of Hawker Beechcraft Mandatory Service Bulletin SB 32-3920, dated August 2008, specifies a compliance time of within 200 flight cycles since installation of the affected MLG assembly, or within 60 days after the receipt of the service bulletin, whichever occurs first, this AD does not include that compliance time. We have determined that a compliance time of 30 days after the effective date of this AD is necessary to address the unsafe condition. In developing an appropriate compliance time of this AD, we considered the manufacturer's recommendation, the degree of urgency associated with the subject unsafe condition, the average utilization of the affected fleet, and the time necessary to perform the inspection. The difference has been coordinated with Hawker Beechcraft Corporation.
Although the Accomplishment Instructions of Hawker Beechcraft Mandatory Service Bulletin SB 32-3920, dated August 2008, specify the following actions, this AD does not include those requirements.
Contact the manufacturer if no affected serial number is found;
Return spare parts to the manufacturer; and
Report accomplishment of the service bulletin.
The Accomplishment Instructions of Hawker Beechcraft Mandatory Service Bulletin SB 32-3920, dated August 2008, specify to inspect for serial numbers on the MLG assembly to determine if any MLG assembly with a serial number identified in Table 1 of the service bulletin is installed on the airplane. The accomplishment instructions do not specify an inspection to determine if any part identified in the ``spares'' paragraph 1.A.(2) of the service bulletin is installed. In order to address all affected parts, this AD requires doing an inspection to determine if the serial number and part number of the MLG upper casings are from either Table 1 or paragraph 1.A.(2) of the service bulletin.
FAA's Justification and Determination of the Effective Date
Improper hydrogen embrittlement relief of the MLG casings could result in a fracture of the MLG casings and a collapse of the affected MLG, which could adversely affect the airplane's continued safe flight and landing. Because of our requirement to promote safe flight of civil aircraft and thus, the critical need to assure the proper functioning of the MLG assembly 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 that 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.
Comments Invited
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-2008-0976; Directorate Identifier 2008-NM-145-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.
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
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.
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 FAA amends Sec. 39.13 by adding the following new AD: