Page:CAB Accident Report, Pennsylvania-Central Airlines Flight 143.pdf/27

 a structural failure might result. Captain Wright increased the manifold pressure to 36½ inches for a few seconds in order to clear the secondary high tension line. Thirty-four inches of manifold pressure were used in the left engine after the airplane had cleared this line. The aircraft airworthiness certificate of the airplane authorized operation of the engines at maximums of 35½ inches of manifold pressure for one minute during take-off and 35 inches for cruising at sea level. The manifold pressure maximum varied lineally from 35 inches for cruising at sea level to 33 inches for cruising at 8,000 feet. These limitations did not apply to emergency situations and the certificate did not specify what amount, if any, of additional power might be used in an emergency. Only when Captain Wright saw that a crash was imminent because of the steep rise of the terrain at the top of the valley did he again exercise his emergency power under Section 61.7811 of the Civil Air Regulations and increase the manifold pressure above 34 inches. He increased it to 42½ inches at this time and placed the airplane in a steep, climbing attitude so as to make a stall landing into the trees on the side of the ridge. This, he believed, was the course involving the least possible danger.

The PCA Superintendent of Maintenance testified that "34 inches of manifold pressure at 2200 r.p.m. is normal take-off power. However, instructions are also set up that for maximum power 35½ inches at 2200 r.p.m. is permissible." He further stated that he believed "the engine could be operated at short intervals up to 40 inches" manifold pressure and that the engine "could be used in