46-13-03 LOCKHEED: (Was Mandatory Note 6 of AD-723-2.) Applies to Model 18 Aircraft.
Compliance required before next 10 hours of operation.
The oil tanks should be examined to determine whether or not they are of the hopper type, and appropriate action in one of the following manners must be taken:
1. If a hopper type oil tank is installed and is to be retained in accordance with Note 14(b) of Aircraft Specification A-723-4 (for use with oil dilution), the following action must be taken (applies only to Serial Numbers 2294 and up):
(a) Install a propeller feathering reserve oil tank (P/N 174399) forward of the firewall. (Lockheed Service Bulletin No. 18/SB-115 dated April 18, 1945, covers this same subject.)
(b) Rework the hopper assembly to provide better support at the sump by installing a new support assembly (P/N 174321). At each engine change, remove plate and elbow on bottom of sump housing (P/N 114690) and inspect hopper with a light and mirror. (Lockheed Service Bulletin No. 18-99 dated September 29, 1943, covers this same subject.)
2. If the hopper type oil tank is to be removed, the following action must be taken (applies only to Serial Numbers 2294 and up, except Serial Numbers 2359, 2403, 2464, and 2465):
Remove the hopper type oil tank and propeller feathering lines and replace with a conventional type tank (P/N 73662), fitted with a standpipe to provide a reservoir of oil for propeller feathering, and install a separate feathering line from the oil tank to the feathering pump. (Lockheed Service Bulletin No. 18-100 dated March 3, 1944, covers this same subject.)
3. On airplanes which have conventional oil tanks other than P/N 73662, the standpipe at the outlet in each tank must be revised in one of the following manners, whichever is applicable. (Applies to all Series 18 airplanes, except Models 18-07 and 18-40, with Serial Numbers 2293 and below, 2359, 2403, 2464, and 2465.)
(a) If the tanks are equipped with the standard 3 31/32-inch long standpipes (P/N 164101), the standpipe in each tank should be removed and a new 4 15/16-inch standpipe (P/N 16401, change D) installed.
b) If the tanks are equipped with oil stick gage foam guards, the existing standpipe in each tank should be cut off near the bottom of the tank, the foam guard cut off approximately 5.38 inches from the bottom surface of the oil tank outlet connection boss, and a new standpipe assembly (P/N 173806) installed.
(Lockheed Service Bulletin No. 18-105 dated October 19, 1943, covers this same subject.)