AD 77-14-04

77-14-04 HAWKER SIDDELEY AVIATION, LTD.: Amendment 39-2952. Applies to DH-104 "Dove" and DH-114 "Heron" airplanes.

Compliance is required within the next 500 hours time in service after the effective date of this AD unless already accomplished.

To prevent the possibility that a loss of generated electrical power would be undetected by the flight crew, accomplish the following:

(a) Alter the electrical system to incorporate a bus bar low voltage sensing unit, a bus bar low voltage warning light, and an essential service switch, designed and installed in accordance with paragraphs 5 and 6 of Hawker Siddeley Aviation, Ltd., Technical News Sheet, Series: Heron (114), No. N. 6., Issue 3 (for DH-114 "Heron") and CT104, No. 227, Issue 3 (for DH-104 "Dove"), both dated July 3, 1972, as amended to November 20, 1972, or FAA-approved equivalent of either.

(b) Amend the "Normal and Emergency Procedures", Part B, of the "Operating Procedures" section, Section II, of the applicable Airplane Flight Manual by adding the electrical system operation information contained in paragraphs 7 and 8 and Figure 1 of the applicable Technical News Sheet, referred to in paragraph (a) of this AD, or an FAA-approved equivalent.

(c) Check the condition of the electrical distribution and generator system in accordance with paragraph 6 of the applicable Technical News Sheet, referred to in paragraph (a) of this AD, or an FAA-approved equivalent, and repair, as necessary. The checks required by this paragraph may be performed by persons authorized to perform preventive maintenance under FAR 43.

This amendment becomes effective August 5, 1977.