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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 99-NM-345-AD] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Notice of proposed rulemaking (NPRM). 

# SUMMARY:

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to all Raytheon Model DH.125-1A, -3A, and -400A series airplanes, that currently requires a one-time inspection to detect scoring of the upper fuselage skin around the periphery of the cockpit canopy blister interface, and repair, if necessary. This action would expand the applicability of the existing AD to include additional airplanes, and would require that the actions be accomplished in accordance with revised service information for the newly added airplanes. This AD is prompted by additional reports indicating that scoring has been detected on the upper fuselage skin around the periphery of the cockpit canopy blister interface. The actions specified by the proposed AD are intended to detect and correct scoring of the upper fuselage skin around the periphery of the cockpit canopy blister interface, which could result in reduced structural integrity of the fuselage, and consequent cabin depressurization. 

# DATES:

Comments must be received by July 31, 2000. 

# ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-345-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays. 

The service information referenced in the proposed rule may be obtained from Raytheon Aircraft Company, Commercial Service Department, 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:

T.N. Baktha, Aerospace Engineer, Airframe Branch, ACE-118W, FAA, Small Airplane Directorate, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316) 946-4155; fax (316) 946-4407. 

# 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                           ( print page 37724)                        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 99-NM-345-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. 99-NM-345-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. 

## Discussion 

On April 24, 1997, the FAA issued AD 97-09-12, amendment 39-10008 (62 FR 24013, May 2, 1997), applicable to all Raytheon Model DH.125-1A, -3A, and -400A series airplanes, to require a one-time inspection to detect scoring of the upper fuselage skin around the periphery of the cockpit canopy blister interface, and repair, if necessary. That action was prompted by reports indicating that scoring of the upper fuselage skin had been detected in the area. The requirements of that AD are intended to detect and correct scoring of the upper fuselage skin around the periphery of the cockpit canopy blister interface, which could result in reduced structural integrity of the fuselage, and consequent cabin depressurization. 

## Actions Since Issuance of Previous Rule 

Since the issuance of that AD, the FAA has received numerous reports indicating that scoring has been detected on the upper fuselage skin around the periphery of the cockpit canopy blister interface. Investigation revealed that the scoring was caused by the use of an improper tool (Exacto knife), which was used to remove excess sealant along the interface of the fuselage skin and the cockpit canopy. In light of these additional reports, the FAA has determined that certain Raytheon Model BH.125, DH.125, and HS.125 series airplanes may be subject to the identified unsafe condition. 

## Issuance of Revised Service Information 

The FAA has reviewed and approved Raytheon Aircraft Service Bulletin SB 53-93, Revision 2, dated April 2000. The inspection and repair procedures described in this revision are identical to those described in the original issue of the service bulletin (which is referenced in AD 97-09-12). However, this revision expands the effectivity listing to include additional airplanes that are subject to the addressed 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 supersede AD 97-09-12 to continue to require a one-time inspection to detect scoring of the upper fuselage skin around the periphery of the cockpit canopy blister interface, and repair, if necessary. This action would expand the applicability of the existing AD to include additional airplanes that may also be subjected to the identified unsafe condition. The actions would be required to be accomplished in accordance with the service bulletin described previously. 

## Cost Impact 

There are approximately 290 airplanes of the affected design in the worldwide fleet. The FAA estimates that 200 airplanes of U.S. registry would be affected by this proposed AD. 

The actions that are currently required by AD 97-09-12 and retained in this proposed AD would take approximately 4 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the currently required actions on U.S. operators is estimated to be $48,000, or $240 per airplane. 

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the current or proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. 

## 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 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 removing amendment 39-10008 (62 FR 24013, May 2, 1997), and by adding a new airworthiness directive (AD), to read as follows: 

**Raytheon Aircraft Company:**                                 Docket 99-NM-345-AD. Supersedes AD 97-09-12, Amendment 39-10008.                             

*Applicability:*                                 Model DH.125, BH.125, and HS.125 series airplanes as listed in Raytheon Aircraft Service Bulletin SB 53-93, Revision 2, dated April 2000; 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 (e) 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                                           ( print page 37725)                                        been eliminated, the request should include specific proposed actions to address it.                                

*Compliance:*                                 Required as indicated, unless accomplished previously.                             

To detect and correct scoring of the upper fuselage skin around the periphery of the cockpit canopy blister interface, which could result in reduced structural integrity of the fuselage skin, and consequent cabin depressurization; accomplish the following: 

## Restatement of the Requirements of AD 97-09-12

(a) For Model DH.125-1A, -3A, and -400A series airplanes as identified in Raytheon Aircraft Service Bulletin SB 53-93, dated May 16, 1996: Within 90 days after June 6, 1997 (the effective date of AD 97-09-12, amendment 39-10008), perform a one-time detailed visual inspection to detect scoring of the upper fuselage skin around the periphery of the cockpit canopy blister interface, in accordance with the service bulletin. 

(b) If no scoring is detected during the inspection required by paragraph (a) of this AD, no further action is required by this AD. 

(c) If any scoring is detected during the inspection required by paragraph (a) of this AD, prior to further flight, determine the maximum location and details of each score, including the edge distance and material thickness, in accordance with Raytheon Aircraft Service Bulletin SB 53-93, dated May 16, 1996. 

(1) If any scoring is found that is within the limits specified in the service bulletin, prior to further flight, repair in accordance with the service bulletin. 

(2) If any scoring is found that is outside the limits specified in the service bulletin, prior to further flight, repair in accordance with a method approved by the Manager, Wichita Aircraft Certification Office (ACO), FAA, Small Airplane Directorate. 

## New Requirements of This AD

(d) For airplanes identified in Raytheon Aircraft Service Bulletin SB 53-93, Revision 2, dated April 2000, and not previously identified in paragraph (a) of this AD: Within 90 days after the effective date of this AD, perform a one-time detailed visual inspection to detect scoring of the upper fuselage skin around the periphery of the cockpit canopy blister interface, in accordance with Raytheon Aircraft Service Bulletin SB 53-93, Revision 2, dated April 2000. 

(1) If no scoring is detected during the inspection required by paragraph (d) of this AD, no further action is required by this AD. 

(2) If any scoring is detected during the inspection required by paragraph (d) of this AD, prior to further flight, determine the location and details of each score, including the edge distance and material thickness, in accordance with the service bulletin. 

(i) If any scoring is found that is within the limits specified in the service bulletin, prior to further flight, repair in accordance with the service bulletin. 

(ii) If any scoring is found that is outside the limits specified in the service bulletin, prior to further flight, repair in accordance with a method approved by the Manager, Wichita ACO. 

# Note 2:

Any inspections and repairs accomplished prior to the effective date in accordance with Raytheon Service Bulletin SB 53-93, Revision 1, dated April 1999, are considered acceptable for compliance for the applicable actions required by this AD.

## Alternative Methods of Compliance 

(e) 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 ACO. 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 

(f) 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 June 12, 2000. 

Donald L. Riggin, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 00-15310 Filed 6-15-00; 8:45 am] 

BILLING CODE 4910-13-U