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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 98-NM-368-AD] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Notice of proposed rulemaking (NPRM). 

# SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Raytheon (Beech) Model MU-300, MU-300-10, 400, and 400A series airplanes. This proposal would require repetitive inspections of the bleed air supply tube assemblies for discrepancies; and replacement of the bleed air tube assembly with a new bleed air tube assembly, if necessary. In lieu of accomplishing the repetitive inspections, this proposal also would provide for a revision of the Airworthiness Limitations to incorporate, among other things, certain inspections and compliance times to detect discrepancies of the subject area; and corrective action, if necessary. This proposal is prompted by reports of broken wire braiding in the bellows assembly of the bleed air supply tube assembly due to premature failure from loading. The actions specified by the proposed AD are intended to prevent the bleed air supply tube assembly from disconnecting and contacting other pneumatic or electrical systems of the airplane or expelling high temperature air on surrounding systems and structure. Such a condition could reduce the functional capabilities of the airplane or the ability of the flight crew to cope with adverse operating conditions. 

# DATES:

Comments must be received by June 26, 2000. 

# ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 98-NM-368-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. 

The service information referenced in the proposed rule may be obtained from Raytheon Aircraft Company, Manager Service Engineering, Beechjet Premier Technical Support, P.O. Box 85, Wichita, Kansas 67201-0085. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Small Airplane Directorate, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas. 

# FOR FURTHER INFORMATION CONTACT:

                        Paul C. DeVore, Aerospace Engineer, Systems and Propulsion Branch, ACE-116W, FAA, Small Airplane Directorate, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas, 67209, telephone, (316) 946-4142; fax, (316) 946-4407.                               ( print page 30032)    

# SUPPLEMENTARY INFORMATION:

## Comments Invited 

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received. 

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 FAA-public 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 self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 98-NM-368-AD.” 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, ANM-114, Attention: Rules Docket No. 98-NM-368-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. 

## Discussion 

The FAA has received reports of broken wire braiding in the bellows assembly of the bleed air supply tube assembly on Raytheon (Beech) Model MU-300, MU-300-10, 400, and 400A series airplanes. Investigation revealed that the stainless steel wire mesh braiding that restrains the bellows is subject to loading, which causes the braiding to fail prematurely. Failure of the wire braiding, if not corrected, could cause the bleed air supply tube assembly to disconnect and contact other pneumatic or electrical systems of the airplane or expel high temperature air on surrounding systems and structure. Such a condition could reduce the functional capabilities of the airplane or the ability of the flight crew to cope with adverse operating conditions. 

## New Revisions to Airworthiness Limitations Section 

The FAA has reviewed and approved Chapter 4, “Airworthiness Limitations” of Raytheon Aircraft Beechjet 400/400A Maintenance Manual (for Model MU-300-10, 400, and 400A series airplanes), Revision B23, dated December 18, 1998, and Section MR-11-00, “Airworthiness Limitations” of Raytheon Aircraft Diamond 1/1A MU-300 Maintenance Requirement Manual (for Model MU-300 series airplanes), Revision 8, dated December 18, 1998. These revisions describe, among other things, specific inspection and compliance times to detect broken wire braids, leakage, or rupture of the bellows assembly in the bleed air supply tube assembly; and corrective action, if necessary. The corrective action involves replacement of the bleed air tube assembly with a new bleed air tube assembly. Accomplishment of the procedures specified in the Airworthiness Limitations Section (ALS) or the repetitive inspections described below 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 repetitive general visual inspections of the bleed air supply tube assemblies for broken wire braiding on the bellows assemblies or for ruptured or leaking bellow assemblies; and replacement of the bleed air tube assembly with a new bleed air tube assembly, if necessary. In lieu of accomplishing the repetitive inspections, the proposed AD also would provide for a revision of the ALS of Raytheon Aircraft Beechjet 400/400A Maintenance Manual (for Model MU-300-10, 400, and 400A series airplanes), and Raytheon Aircraft Diamond 1/1A MU-300 Maintenance Manual (for Model MU-300 series airplanes) to incorporate Revision B23, dated December 18, 1998 (for Model MU-300-10, 400, and 400A series airplanes), and Revision 8, dated December 18, 1998 (for Model MU-300 series airplanes); as applicable. 

## Cost Impact 

There are approximately 530 airplanes of the affected design in the worldwide fleet. The FAA estimates that 452 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 1 work hour per airplane to accomplish the proposed inspection, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $27,120, or $60 per airplane, per inspection cycle. 

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 AD were not adopted. 

Should an operator elect to accomplish the optional terminating action that would be provided by this AD action, it would take approximately 1 work hour to accomplish it, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the optional terminating action would be $60 per airplane. 

## Regulatory Impact 

The regulations proposed herein would not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. 

                    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: 

      ( print page 30033)    

# 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 

2. Section 39.13 is amended by adding the following new airworthiness directive: 

**Raytheon Aircraft Company (Formerly Beech):**                                 Docket 98-NM-368-AD.                             

*Applicability:*                                 All Model MU-300, MU-300-10, 400, and 400A series airplanes, 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 (d) 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 the bleed air supply tube assembly from disconnecting and contacting other pneumatic or electrical systems of the airplane or expelling high temperature air on surrounding systems and structure, which could result in reduced functional capabilities of the airplane or the ability of the flight crew to cope with adverse operating conditions; accomplish the following: 

## Inspection 

(a) Within 200 hours time-in-service after the effective date of this AD, except as provided by paragraph (b) of this AD, perform a general visual inspection of the bleed air supply tube assemblies for broken wire braiding on the bellows assemblies or for ruptured or leaking bellow assemblies. The bleed air supply tube assemblies are located within the aft fuselage and connect to mating ducting in the pylon area on the right and left side of the airplane. Repeat the inspection thereafter at intervals not to exceed 400 hours time-in-service. If any broken wire is detected or if any bellow assembly is ruptured or leaking, prior to further flight, replace the bleed air tube assembly with a new bleed air tube assembly. 

# 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 drop-light, 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.”

## Optional Implementation of Airworthiness Limitations Section 

(b) Instead of accomplishing the requirements of paragraph (a) of this AD, revise the Airworthiness Limitations Sections of the Instructions for Continued Airworthiness by incorporating the procedures specified in Chapter 4, “Airworthiness Limitations” of Raytheon Aircraft Beechjet 400/400A Maintenance Manual, Revision B23, dated December 18, 1998 (for Model MU-300-10, 400, and 400A series airplanes); or Section MR-11-00, “Airworthiness Limitations” of Raytheon Aircraft Diamond 1/1A MU-300 Maintenance Requirement Manual, Revision 8, dated December 18, 1998 (for Model MU-300 series airplanes); as applicable. 

(c) Except as provided in paragraph (d) of this AD: After the action specified in paragraph (b) of this AD has been accomplished, no alternative inspections or inspection intervals may be approved for the part specified in paragraph (b) of this AD. 

## Alternative Methods of Compliance 

(d) 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 Permits 

(e) Special flight permits may be issued in accordance with § 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 May 3, 2000. 

Vi L. Lipski, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 00-11720 Filed 5-9-00; 8:45 am] 

BILLING CODE 4910-13-U