AD 99-07-09

This amendment adopts a new airworthiness directive (AD) that applies to certain British Aerospace Jetstream Model 3201 airplanes. This AD requires replacing the nose landing gear downlock actuator, the flap actuator, the steering selector valve, the hydraulic reservoir,
and the emergency selector valve. This AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for the United Kingdom. The actions specified by this AD are intended to prevent internal corrosion of the hydraulic components on
airplanes where these components were exposed to water contamination, which could result in reduced or loss of control of the airplane.

Final rule

99-07-09 BRITISH AEROSPACE: Amendment 39-11094; Docket No. 98-CE-91-AD. Applicability: Jetstream Model 3201 airplanes, constructor numbers 841, 842, 844 through 848, 851, 853 through 855, 857, 859 through 862, and 864; 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 (c) 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 at whichever of the following occurs later, unless already accomplished:

1. Upon accumulating 8,000 landings on the airplane or within 5 years since the last time the hydraulic system components were replaced (see paragraph (a) of this AD for listing of components), whichever occurs first; or

2. Within the next 12 calendar months after the effective date of this AD.

NOTE 2: If the number of landings is unknown, hours time-in-service (TIS) may be used by dividing 8,000 by 0.75. If hours TIS are utilized to calculate the number of landings, this would calculate the 8,000 landings compliance time to 10,667 hours TIS.

To prevent internal corrosion of the hydraulic components on airplanes where these components were exposed to water contamination, which could result in reduced or loss of control of the airplane, accomplish the following:

(a) Replace the following critical components of the hydraulic system, in accordance with the applicable maintenance manual, as specified in Jetstream Alert Service Bulletin 29-A-JA 970940, Original Issue: February 4, 1998, or Jetstream Alert Service Bulletin 29-A-JA 970940, Original Issue: February 4, 1998, Revision No. 1: January 27, 1999:

(1) the nose landing gear downlock actuator;

(2) the flap actuator;

(3) the steering selector valve;

(4) the hydraulic reservoir; and

(5) the emergency selector valve.

NOTE 3: The FAA highly recommends replacing the hydraulic fluid while these system components are being replaced, as specified in Jetstream Alert Service Bulletin 29-A-JA 970940, Original Issue: February 4, 1998, or Jetstream Alert Service Bulletin 29-A-JA 970940, Original Issue: February 4, 1998, Revision No. 1: January 27, 1999.

(b) 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 thisAD can be accomplished.

(c) An alternative method of compliance or adjustment of the compliance time that provides an equivalent level of safety may be approved by the Manager, Small Airplane Directorate, Aircraft Certification Service, 1201 Walnut, suite 900, Kansas City, Missouri 64106. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Small Airplane Directorate.

NOTE 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Small Airplane Directorate.

(d) Questions or technical information related to British Aerospace Jetstream Alert Service Bulletin 29-A-JA 970940, Original Issue: February 4, 1998, or Jetstream Alert Service Bulletin 29-A-JA 970940, Original Issue: February 4, 1998, Revision No. 1: January 27, 1999, should be directed to British Aerospace Regional Aircraft, Prestwick International Airport, Ayrshire, KA9 2RW, Scotland; telephone: (01292) 479888; facsimile: (01292) 479703.

This service information may be examined at the FAA, Central Region, Office of the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106.

NOTE 5: The subject of this AD is addressed in British AD 001-02-98, not dated.

(e) This amendment becomes effective on May 10, 1999.

Events Leading to the Issuance of This AD
A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to certain British Aerospace Jetstream Model 3201 airplanes was published in the Federal Register as a notice of proposed rulemaking (NPRM) on December 8, 1998 (63 FR 67633). The NPRM proposed to require replacing the nose landing gear downlock actuator, the flap actuator, the steering selector valve, the hydraulic reservoir, and the emergency selector valve. Accomplishment of the proposed action as specified in the NPRM would be in accordance with the applicable maintenance manual, as specified in Jetstream Alert Service Bulletin 29-A-JA 970940, Original Issue: February 4, 1998.

The NPRM was the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for the United Kingdom.

Interested persons have been afforded an opportunity to participate in themaking of this amendment. No comments were received on the proposed rule or the FAA's determination of the cost to the public.

Since the issuance of the NPRM, British Aerospace has revised Jetstream Alert Service Bulletin 29-A-JA 970940, Original Issue: February 4, 1998 (Revision No. 1: January 27, 1999). This service bulletin revision only corrects reference to parts, clarifies certain aspects of the subjects, and incorporates procedural changes. In addition, the service bulletins (both the original issue and Revision No. 1) only specify the replacements. The procedures for accomplishing the work are included in the maintenance manual.

The FAA's Determination
After careful review of all available information related to the subject presented above, the FAA has determined:

--that referencing the revised service information in the AD would not add any additional burden upon the public than was originally proposed; and

--that air safety and the public interest require theadoption of the rule as proposed except for minor editorial corrections.

Compliance Time of This AD
The compliance time of this AD is presented in both calendar time and hours time-in-service (TIS). Corrosion could occur on the hydraulic system components and then either continue to deteriorate the part over time regardless of airplane operation or develop into stress cracks over time based on airplane operation. In order to assure that this condition does not go undetected, a compliance time of specific hours TIS and calendar time is utilized.

Cost Impact
The FAA estimates that 9 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 33 workhours per airplane to accomplish this action, and that the average labor rate is approximately $60 an hour. Parts to accomplish the replacements cost approximately $46,636. (Overhauled or repaired parts are available from the agencies of equipment manufacturers or from the aircraft manufacturer's agency). Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $437,544, or $48,616 per airplane.

Regulatory Impact
The regulations adopted herein will 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 final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action (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. A copy of the final 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.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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 a new airworthiness directive (AD) to read as follows: