AD 98-21-28 ACTIVE

This action confirms the effective date of Airworthiness Directive (AD) 98-21-28, which applies to certain British Aerospace Jetstream Model 3101 airplanes. AD 98-21-28 requires modifying the propeller de-icing system to assure system performance at low ambient temperatures. This AD was the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for the United Kingdom. The actions specified in this AD are intended to prevent propeller-induced vibrations from occurring during icing encounters at low ambient temperatures, which could result in decreased performance of the de-icing system during icing encounters with possible loss of control of the airplane.

Direct final rule; confirmation of effective date

98-21-28 BRITISH AEROSPACE: Amendment 39-10836; Docket No. 98-CE-63-AD.
Applicability: Jetstream Model 3101 airplanes, serial numbers 601 through 645, 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 within the next 100 hours time-in-service (TIS)after the effective date of this AD, unless already accomplished.

To prevent propeller-induced vibrations from occurring during icing encounters at low ambient temperatures, which could result in decreased performance of the de-icing system during icing encounters with possible loss of control of the airplane, accomplish the following:

(a) Modify the propeller de-icing system by incorporating the following modifications in accordance with Jetstream Service Bulletin 30-JM 7453, ORIGINAL ISSUE: October 24, 1984, REVISION 2: December 10, 1984:

(1) Modification No. JM 7398: Ice Protection - Introduction of Revised Propeller De-Ice Circuit.

(2) Modification No. JM 7407: Ice and Rain Protection - Introduction of Dowty Rotol Dual Brush Block Assembly in Propeller De-icing Systems.

(3) Modification No. JM 7408: Propeller - Introduction of Propeller Incorporating Slipring to Dowty Rotol Mod VP3062.

(4) Modification No. JM 7445: Propeller - Introduction ofPropeller with Revised 21-inch Boots.

(5) Modification No JM 7449: Ice and Rain Protection - Introduction of Dowty Rotol Dual Rate Timer, Revised Ammeter, Selector Switch, and Fuses.

(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 this AD can be accomplished.

(c) An alternative method of compliance or adjustment of the compliance time that provides an equivalent level of safety may be used if 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 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any,may be obtained from the Small Airplane Directorate.

(d) The modifications required by this AD shall be done in accordance with Jetstream Service Bulletin 30-JM 7453, ORIGINAL ISSUE: October 24, 1984, REVISION 2: December 10, 1984. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from British Aerospace Regional Aircraft, Prestwick International Airport, Ayrshire, KA9 2RW, Scotland. Copies may be inspected at the FAA, Central Region, Office of the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at the Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

NOTE 3: The subject of this AD is addressed in Jetstream Service Bulletin 30-JM-7453, ORIGINAL ISSUE: October 24, 1984, REVISION 2: December 10, 1984. This service bulletin is classified as mandatory by the United Kingdom Civil Aviation Authority(CAA).

(e) This amendment becomes effective on January 15, 1999

The FAA published this direct final rule with request for comments in the Federal Register on October 14, 1998 (63 FR 55015). The FAA uses the direct final rulemaking procedure for a non-controversial rule where the FAA anticipates that there will be no adverse public comment. This direct final rule advised the public that no adverse comments were anticipated, and that unless a written adverse comment, or a written notice of intent to submit such an adverse comment, was received within the comment period, the regulation would become effective on January 15, 1999. No adverse comments were received, and thus this notice confirms that this final rule will become effective on that date.

Mr. S.M. Nagarajan, Aerospace Engineer, FAA, Small Airplane Directorate, 1201 Walnut, suite 900, Kansas City, Missouri 64106; telephone: (816) 426-6932; facsimile: (816) 426-2169.