AD 55-15-05

55-15-05 DOUGLAS: Applies to All DC-7 Aircraft Below Fuselage No. 486 Equipped With Hamilton Standard Propellers.

Compliance required by first scheduled engine change after November 1, 1955, but not later than November 1, 1956.

To increase the integrity of the propeller feathering system in the event of a powerplant fire, all existing propeller feathering lines located forward of the firewall in zone 2 must be replaced with lines and flexible hose assemblies which will meet current fireproof and fire resistant requirements.

(a) Install Aeroquip 304 protective sleeves on the propeller feathering line forward of the feathering pump, in accordance with Aeroquip Drawing 304005-10S-46. Resistoflex SSFR-3800-10 hose assembly and Aeroquip 309009-10S hose assembly are also considered acceptable for this application.

(b) Remove the existing short 304 sleeves from the feathering pump supply line between the oil tank and feathering pump and install a fireproof cover, Douglas P/N 3500614-2. Aeroquip 601000 hose assembly equipped with Aeroquip 304 full-length protective sleeve, or Aeroquip 680-16S hose assembly equipped with Aeroquip 304 short sleeves covering the end fittings are also considered acceptable for this application.

(Douglas Service Bulletin DC-7 No. 74 dated July 19, 1955, covers this same subject.)