AD 72-18-09

72-18-09 BRITISH AIRCRAFT CORPORATION: Amendment 39-1514. Applies to Vickers Viscount, Model 744, 745D and 810 airplanes.

Compliance is required as indicated.

To reduce the vulnerability of control rods, electrical systems, and structure located in the underfloor electrical system bay to fire and overheat damage, accomplish the following:

(a) For Models 744, 745D and 810 airplanes with nickel-cadmium batteries in the primary electrical system, within the next 250 hours' time in service after the effective date of this AD, unless already accomplished, replace the control rods in accordance with paragraph (e) and replace the electrical panel guard covers in accordance with paragraph (f).

(b) For Models 744 and 745D airplanes with nickel-cadmium batteries in the primary electrical system, within the next 250 hours' time in service after the effective date of this AD, unless already accomplished, install protective surfaces on the lower surface of floor panels in accordance with paragraph (g).

(c) For Models 744, 745D and 810 airplanes with lead acid batteries in the primary electrical system within the next 1500 hours' time in service after the effective date of this AD, unless already accomplished, replace the control rods in accordance with paragraph (e) and replace the electrical panel guard covers in accordance with paragraph (f).

(d) For Models 744 and 745D airplanes with lead acid batteries in the primary electrical system, within the next 1500 hours' time in service after the effective date of this AD, unless already accomplished, install protective panels on the lower surface of floor panels in accordance with paragraph (g).

(e) Replace applicable control rods listed in Column A with the control rods listed in Column B:

(1) For Models 744 and 745D airplanes :

COLUMN A Remove Part Numbers COLUMN B Install Part Numbers

70133 Sht. 97 70133 Sht. 231 Aileron 70133 Sht. 185 70133 Sht. 235

70133 Sht.93 70133 Sht. 227 Elevator 70133 Sht. 95 70133 Sht. 229

70133 Sht. 93 70133 Sht. 227 Rudder 70133 Sht. 95 70133 Sht. 229

(2) For Model 810 airplanes:

COLUMN A Remove Part Numbers COLUMN B Install Part Numbers

70133 Sht. 97 70133 Sht. 231 Aileron 80233 Sht. 31 80233 Sht. 391

70133 Sht. 93 70133 Sht. 227 Elevator 70133 Sht. 153 70133 Sht. 233

70133 Sht. 93 70133 Sht. 227 Rudder 70133 Sht. 153 70133 Sht. 233

(f) Replace Perspex electrical panel covers listed in Column A with glasscloth resin laminate covers listed in Column C, or FAA-approved equivalent covers.

(1) For Models 744 and 745D airplanes:

COLUMN A COLUMN B COLUMN C Remove Part Numbers Location Install Part Numbers

72436-1903

74536-315

Over fuses at top of power panel "K"

At cut-out for control rods at top of power panel "J"

72436 Sht. 735

74536-1481 72436-663 Over wing root panel "H" 72436 Sht. 737 72436-665 Over wing rootpanel "G" 72436 Sht. 739

(2) For Model 810 airplanes:

COLUMN A COLUMN B COLUMN C Remove Part Numbers Location Install Part Numbers 81236-2713 Over wing root panel "H" 81236 Sht. 147 81236-2715 Over wing root panel "G" 81236 Sht. 149

(g) Install 2024 aluminum alloy sheeting with a minimum thickness of .028 inches, or an FAA-approved equivalent fire resistant material, on the lower surface of all floor panels made of plywood or material with similar fire resistant characteristics, between fuselage stations 357.85 and 414.00.

(British Aircraft Corporation Bulletins for Modification D.3249 (700 Series) and FG.2127 (800/810 Series) cover this same subject).

This amendment becomes effective 6 September 1972.