Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAApublic contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a selfaddressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 2000NM60AD.'' The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM114, Attention: Rules Docket No. 2000NM60AD, 1601 Lind Avenue, SW., Renton, Washington 980554056.

Discussion

The FAA has received a report indicating that hydraulic fluid leakage has occurred on certain Raytheon (Beech) Model MU300, MU300 10, 400, 400A, and 400T series airplanes. The existing design of the hydraulic tube installation for the left wheel of the landing gear includes an unsupported hydraulic line (tube), which is vulnerable to vibrations or mishandling. This unsupported hydraulic tube was found to have fatigue cracks around the flared end of the tube causing hydraulic fluid to leak from the fittings (Bnut area). Such leakage could progress to a sudden loss of normal braking to the left wheel resulting in an asymmetric braking condition and a longer stopping distance. This condition, if not corrected, could result in the airplane overrunning the runway surface.

Explanation of Relevant Service Information

The FAA has reviewed and approved Raytheon Aircraft Service Bulletin SB 323300, dated December 1999, which describes procedures for a onetime inspection to detect hydraulic fluid leakage from the B nut area, which attaches a hydraulic tube to the antiskid valve assembly, and corrective actions, if necessary. The corrective actions involve the installation of a new or serviceable hydraulic tube if hydraulic fluid leakage is found. The service bulletin also describes procedures for the installation of an additional support for the hydraulic tube, which involves the installation of a new nutplate, clamp, and screw. Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require accomplishment of the actions specified in the service bulletin described previously.

Cost Impact

There are approximately 567 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 522 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 2 work hours per airplane to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Required parts would cost approximately $31 per airplane. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $78,822, or $151 per airplane.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this proposed AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions. Additionally, the manufacturer has indicated the warranty remedies may be available to defer the cost of the replacement parts also associated with accomplishing this actions required by this proposed AD.

Regulatory Impact

The regulations proposed herein 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. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that 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) if promulgated, 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. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES. List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety. The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39AIRWORTHINESS 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. Section 39.13 is amended by adding the following new airworthiness directive:
Raytheon Aircraft Company (Formerly Beech): Docket 2000NM60AD.

Applicability: Model MU300, MU30010, 400, 400A, and 400T series airplanes; as listed in Raytheon Aircraft Service Bulletin [[Page 48947]]
SB 323300, dated December 1999; certificated in any category.

Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (b) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent an asymmetric braking condition and a longer stopping distance due to sudden loss of normal braking to the left wheel, which could result in the airplane overrunning the runway surface, accomplish the following:
General Visual Inspection
(a) Within 200 flight hours after the effective date of this AD, perform a onetime general visual inspection to detect hydraulic fluid leakage from the Bnut area, which attaches a hydraulic tube to the antiskid valve assembly, in accordance with Raytheon Aircraft Service Bulletin SB 323300, dated December 1999.

Note 2: For the purposes of this AD, a general visual inspection is defined as: ``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 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.''
(1) If no leakage is found, prior to further flight, install an additional support (i.e., new nutplate, clamp, and screw) for the hydraulic tube; in accordance with the service bulletin.
(2) If any leakage is found, prior to further flight, replace the hydraulic tube with a new or serviceable hydraulic tube, and install an additional support (i.e., new nutplate, clamp, and screw) for the hydraulic tube; in accordance with the service bulletin. Alternative Methods of Compliance
(b) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Wichita Aircraft Certification Office (ACO), FAA, Small Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Wichita ACO.

Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Wichita ACO.
Special Flight Permit
(c) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Issued in Renton, Washington, on August 3, 2000. Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 0020245 Filed 8900; 8:45 am] BILLING CODE 491013P

FOR FURTHER INFORMATION CONTACT

Paul C. DeVore, Aerospace Engineer, Systems and Propulsion Branch, ACE116W, FAA, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, MidContinent Airport, Wichita, Kansas, 67209, telephone, (316) 9464142; fax, (316) 9464407.