Airworthiness Directives; Raytheon Model BAe.125 Series 1000A and 1000B Airplanes and Model Hawker 1000 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-80-AD]

RIN 2120-AA64

Airworthiness Directives; Raytheon Model BAe.125 Series 1000A and

1000B Airplanes and Model Hawker 1000 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness

directive (AD) that is applicable to all Raytheon Model BAe.125 series

1000A and 1000B airplanes and Model Hawker 1000 series airplanes. This

proposal would require an inspection to determine the integrity of the

duct connection on both ends of the turbine air discharge duct in the

air conditioning system, an inspection to measure the bead height on

the ends of the turbine air discharge duct; and corrective actions, if

necessary. This proposal is prompted by reports indicating that the

turbine air discharge duct disconnected from the cold air unit (CAU) or

water separator due to insufficient bead height on the ends of the

turbine air discharge duct. The actions specified by the proposed AD

are intended to prevent such disconnection from the CAU or water

separator, which could result in cabin depressurization.

DATES: Comments must be received by November 29, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-114,

Attention: Rules Docket No. 99-NM-80-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, Manager Service Engineering,

Hawker Customer Support 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-ContinentAirport, 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.

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.

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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-80-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-80-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The FAA has received several reports indicating that the turbine

air discharge duct disconnected from the cold air unit (CAU) or water

separator in flight on Raytheon Model BAe.125 series 1000A and 1000B

airplanes and Model Hawker 1000 series airplanes during flight.

Investigation revealed that the bead height on the ends of the turbine

air discharge duct was smaller than the design requirement, which could

allow the rubber connecting sleeves to disconnect. Disconnection of the

turbine air discharge duct from the CAU or water separator could result

in loss of normal air supply to maintain cabin pressurization.

Explanation of Relevant Service Information

The FAA has reviewed and approved Raytheon Aircraft Service

Bulletin SB 21-3108, dated November 1998, which describes procedures

for a one-time visual inspection to determine the integrity of the duct

connection on both ends of the turbine air discharge duct in the air

conditioning system; a one-time detailed inspection to measure the bead

height on the ends of the turbine air discharge duct; and corrective

actions, if necessary. The corrective actions involve adjustment of the

clamps, and either rework of the duct or replacement of the duct with a

new duct. 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 52 airplanes of the affected design in the

worldwide fleet. The FAA estimates that 35 airplanes of U.S. registry

would be affected by this proposed AD, that it would take approximately

9 work hours per airplane to accomplish the proposed actions, 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

$18,900, or $540 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 AD were not adopted.

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:

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. Section 39.13 is amended by adding the following new

airworthiness directive:

Raytheon Aircraft Company (Formerly Beech): Docket 99-NM-80-AD.

Applicability: All Model BAe.125 series 1000A and 1000B airplanes

and Model Hawker 1000 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 turbine air discharge duct in the air

conditioning system from disconnecting from the CAU or water

separator in flight, which could result in cabin depressurization,

accomplish the following:

Inspections

(a) Within 25 flight hours after the effective date of this AD,

perform a general visual inspection to determine the integrity of

the duct connections (i.e., ensure that the duct and securing clamps

are in place, the sleeve is central to the joint gap, and the clamps

are clear of the duct bead) on both ends of the turbine air

discharge duct in accordance with Raytheon Service Bulletin SB 21-

3108, dated November 1998. If any discrepancy is detected, prior to

further flight, adjust the clamps in accordance with the service

bulletin.

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-

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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.''

(b) Within 300 flight hours or 6 months after the effective date

of this AD, whichever occurs first, perform a one-time detailed

inspection to measure the bead height on the ends of the turbine air

discharge duct in accordance with Raytheon Service Bulletin SB 21-

3108, dated November 1998. If the bead height does not conform to

the dimension shown in the service bulletin, prior to further

flight, either rework the duct or replace the duct with a new duct,

in accordance with the service bulletin.

Note 3: For the purposes of this AD, a detailed inspection is

defined as: ``An intensive visual examination of a specific

structural area, system, installation, or assembly to detect damage,

failure, or irregularity. Available lighting is normally

supplemented with a direct source of good lighting at intensity

deemed appropriate by the inspector. Inspection aids such as mirror,

magnifying lenses, etc., may be used. Surface cleaning and elaborate

access procedures may be required.''

Spares

(c) As of the effective date of this AD, no person shall install

a turbine air discharge duct, part number 25-9VF425-1A, on any

airplane, unless that duct has been inspected in accordance with

Part II of Raytheon Service Bulletin SB 21-3108, dated November

1998.

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 4: 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

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 October 7, 1999.

D.L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 99-26869 Filed 10-13-99; 8:45 am]

BILLING CODE 4910-13-P