AD 91-18-13

91-18-13 SHORT BROTHERS, PLC: Amendment 39-8015. Docket No. 91-NM-92-AD. Supersedes AD 91-04-06.

Applicability: Model SD3-30 series airplanes, as listed in Short Brothers Service Bulletin SD330-24-25, Revision 2, dated November 29, 1990; and Model SD3-60 series airplanes, as listed in Short Brothers Service Bulletin SD360-24-18, Revision 3, dated November 29, 1990; certificated in any category.

Compliance: Required as indicated, unless previously accomplished.

To prevent loss of power to the pitot/static heaters and subsequent incorrect airspeed and altitude information being provided to the pilot and/or co-pilot in the event of a generator or engine failure, accomplish the following:

A. For Model SD3-30 series airplanes, Serial Numbers SH3002 through SH3072: Within 180 days after the effective date of this AD, revise the power source for the pitot/static heaters, in accordance with Part A of the Accomplishment Instructions in Short Brothers Service Bulletin SD330-24-25, Revision 2, dated November 29, 1990. Following accomplishment of this modification, revise the Emergency and Normal Procedures Sections of the FAA-approved Airplane Flight Manual (AFM) by inserting AFM Amendment Document No. SBH 3.3 (ref. change P/15) or SBH 3.6 (ref. change P/11), as applicable.

B. For Model SD3-30 series airplanes, Serial Numbers SH3073 and subsequent: Within 180 days after the effective date of this AD, revise the power source for the pitot/static heaters, in accordance with Part B of the Accomplishment Instructions in Short Brothers Service Bulletin SD330-24-25, Revision 2, dated November 29, 1990. Following accomplishment of this modification, revise the Emergency and Normal Procedures Sections of the FAA-approved AFM by inserting AFM Amendment Document No. SBH 3.3 (ref. change P/15) or SBH 3.6 (ref. change P/11), as applicable.

C. For Model SD3-60 series airplanes, Serial Numbers SH3601 through SH3619: Within 180 days after the effective date of this AD, revise the power source for the pitot/static heaters, in accordance with the Part A of the Accomplishment Instructions in Short Brothers Service Bulletin SD360-24-18, Revision 3, dated November 29, 1990. Following accomplishment of this modification, revise the Emergency and Normal Sections of the FAA-approved AFM by inserting AFM Amendment Document No. SB 4.3 (ref. change P/18), SB 4.6 (ref. change P/11), or SB 4.8 (ref. change P/8), as applicable.

D. For Model SD3-60 series airplanes, Serial Numbers SH3620 through SH3676: Within 180 days after the effective date of this AD, revise the power source for the pitot/static heaters, in accordance with the Part B of the Accomplishment Instructions in Short Brothers Service Bulletin SD360-24-18, Revision 3, dated November 29, 1990. Following accomplishment of this modification, revise the Emergency and Normal Procedures Sections of the FAA-approved AFM by inserting AFM Amendment Document No. SB 4.3 (ref. change P/18),SB 4.6 (ref. change P/11), or SB 4.8 (ref. change P/8), as applicable.

E. For Model SD3-60 series airplanes, Serial Numbers SH3677 through SH3762: Within 180 days after the effective date of this AD, revise the power source for the pitot/static heaters, in accordance with the Part C of the Accomplishment Instructions in Short Brothers Service Bulletin SD360-24-18, Revision 3, dated November 29, 1990. Following accomplishment of this modification, revise the Emergency and Normal Procedures Sections of the FAA-approved AFM by inserting AFM Amendment Document No. SB 4.3 (ref. change P/18), SB 4.6 (ref. change P/11), or SB 4.8 (ref. change P/8), as applicable.

F. An alternative method of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate.

NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector,who may concur or comment and then send it to the Manager, Standardization Branch, ANM-113.

G. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD.

H. The modification requirement shall be done in accordance with Short Brothers Service Bulletin SD330-24-25, Revision 2, dated November 29, 1990, and Short Brothers Service Bulletin SD360-24-18, Revision 3, dated November 29, 1990. The revisions to the Airplane Flight Manual (AFM) shall be done in accordance with the following list of AFM Amendment Documents and related effective pages:

AFM Amendment Document Number

Page Number

Section Number SBH 3.3 17 37 3 4 SBH.3.6 17 43 3 4 SB.4.3 15 43 3 4 SB.4.6 15 43 3 4 SB.4.8 15 43 3 4

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 Short Brothers, PLC, 2011 Crystal Drive, Suite 713, Arlington, Virginia 22202-3719. Copies may be inspected at the FAA, Transport Airplane Directorate, Renton, Washington; or at the Office of the Federal Register, 1100 L Street N.W., Room 8401, Washington, D.C.

Airworthiness Directive 91-18-13 supersedes AD 91-04-06 Amendment 39-6897.

This amendment (39-8015, AD 91-18-13) becomes effective on October 16, 1991.