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rich, with cylinder head temperatures in the normal range. Backfiring of an engine when a magneto check is made in the automatic lean position is not abnormal at the usual lean settings of most carburetors. With F/A mixtures below best power strength, leaning the mixture reduces flame propagation and speed. With the leaner mixtures, and the consequently lower flame speeds, cutting out one spark plug during the magneto check......does not allow sufficient time to complete combustion of the cylinder charge and to scavenge it by the time the intake valve opens for the next cycle. The still burning cylinder charge ignites the incoming charge, resulting in a backfire. By disregarding this information and unnecessarily creating a backfire, a perfectly good set of plugs can be started on the path of deterioration. Carburetor Heat: Due to the fact that the location of carbureto [[carburetor]] air temperature bulb on the G102 powered aircraft is located downstream of the carburetor, the temperature time measured is that of the mixture and not of the intake air. At this point, the charge temperature is approximately 30-50°F (15-30°C) lower than the temperature of the dry air upstream of the carburetor. Consequently this must be taken into account to prevent detonation during carburetor heat application. In the G102, the maximum limit of mixture temperature for safe engine operation is approximately 60°F and should only be exceeded momentarily to remove ice which has already formed. By keeping the mixture temperature above 32°F, it will be possible under icing condition to avoid the formation of ice. In the P & W engines, the corresponding limit is 100°F (40°C), since the temperature is measured upstream of the carburetor.

BERMUDA

2-19-48 - F.D.Smith

For your information, we are in receipt from the Chief, Inspector, Maintenance Dept., of the following matters of interest.
1. Steps are being taken to relocate the landing gear locks from the position on the forward flight compartment bulkhead to the flight compartment to cabin bulkhead. Reason for this change is to have the gear locks as far as possible away from the magnetic compass.
2. The life rafts are being modified as follows. An Army type fishing kit and additional day's food rations and quantity of sea marker dye are being placed in each raft. This increases the food supply to two days' provisions for 60 people, and adds sea marker dye and fishing kit which were not included previously. 
Mr. Perreault also advises steps have been taken to remove the flight compartment side panels and clean them of hydraulic fluid, fireproof and reinstall same with provisions for periodic fireproofing. Recent complaints regarding cockpit heater overheating are being taken care of with new type switch, which it is felt will eliminate this type of complaint.

Fred D. Smith

FDS: gmo