Page:CAB Accident Report, United Airlines Flight 21.pdf/46

 crankshaft parts, pistons, piston pins, and piston rings were found in normal condition, while slight damage was done to the parts in the main, rear, and intermediate cases. The studs between the cases were bent with a slight chafing indicated at all stud holes, although none was sheared. The blower case showed indications that the impellers had struck the case after the shearing of the accessory shaft, and the impeller blades were scarred slightly. The rear case was cracked at three carburetor support stud holes and also at the hydraulic pump pad.

Right Engine, Serial No. 2624

The intake pipe on the No. 6 cylinder showed evidence of an after fire and the inter-rocker box line hose between cylinders No. 4 and 6 was charred. The intake pipes and pushrod housings were all in place although some were badly crushed. The reduction gear housing had a crack extending from the thrust bearing seat to the attaching flange at the left of the nose section oil pump boss. On the inside, five small cracks were visible on the thrust bearing boss. The support plate assembly showed a small crack at the dowel pin location at the top. The front side of the support plate bore a scar where the propeller shaft had driven back the governor drive gear, indicating a rotation of about 20 degrees. The accessory drive shaft was sheared in a clean vertical break at the undercut in back of the front splines. All crankshaft parts, pistons, piston pins, and piston rings were found in normal condition with very little damage done to the parts in the main, rear, and intermediate cases. The studs between the cases were bent with a slight chafing indicated at all stud holes although none was sheared. The blower case showed indications that the impellers had struck the case after the shearing