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After approximately 10 minutes of climb at this power setting and at airspeeds of from 125 to 130 knots, an indicated altitude of 4,500 feet was attained. The captain stated the first officer then called his attention to the right engine oil inlet temperature gauge which was indicating approximately 115°C. The maximum authorize inlet oil temperature listed in the FAA Approved Flight Manual for AAXICO Airlines is 93°C. The left engine oil inlet temperature gauge still indicated between 95° and 100°C. At this time, the airplane was approximately 20 miles from Malmstrom AFB.
The captain said power was then reduced to 2,250 r.p.m. and 34 inches of hg. and a slow climb was continued. Rate of climb was between zero and 100 feet per minute at this power setting. Oil inlet temperatures lowered at this power setting: the left engine temperature gauge read just under 95°C., and the right reduced to between 100° and 105°C.
After an additional 10 minutes of climb at 2,250 r.p.m. and 34 inches hg., the captain stated he brought the engine power setting back to cruise power for a few minutes. The captain said that shortly thereafter, he realized he needed more altitude and again increased power to 2,400 r.p.m. and 38 inches of hg.
A witness approximately 29 miles east-northeast of Malmstrom AFB and just north of the aircraft's flighpath situated on terrain of approximately 3,500-foot elevation described his observations. "It (the airplane) caught my attention because it was so low. I thought it was going to hit one of the mountains when it came up real slow and just missed it and then dropped quite a bit." (See Attachment I.)
After climb was resumed, the captain reported the right engine oil inlet temperature rose to 120°C., and the oil pressure dropped to 50 pounds.
As the aircraft continued eastward, it flew near the Goldhahn Ranch which is at an elevation of 3,200 feet, and is located 41 nautical miles from Malmstrom AFB, where another witness observed the aircraft. "I saw smoke coming from the right engine. The airplane passed directly over me at about 500 feet altitude. Both engines were working, the gear was retracted and flaps up... As the airplane proceeded east the smoke became more dense and seemed darker, and the airplane seemed to be gaining a little altitude. When it was about five or six miles east of me the smoke disappeared and the plane started to circle to the north. It made a 180-degree turn and proceeded westbound. When it passed to the north of me there wasn't any smoke visible and I couldn't see if the prop was feathered at that time." (See Attachment I.)
Subsequently, the captain said the aircraft had reached approximately 5,500 feet indicated altitude and he observed the right engine oil quantity gauge indicating only 20 gallons of oil remaining of a total of 30 gallons.
Another witness who held a private pilot's license stated he observed the aircraft fly over his ranch still in an eastbound direction. "It was at low altitude, approximately 50 feet above the ground. Its flight attitude was unsteady and the motors were laboring. I observed smoke of black color and major intensity pouring from the right...motor." Subsequently, he observed the aircraft make a turn to the left and fly west back toward the Geraldine Airport. (See Attachment I.)
