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| Title: | Propeller separation, Lake Central Airlines, Inc., Allison Prop-jet Convair 340, N73130, near Marseilles, Ohio, March 5, 1967 |
| Micro summary: | All four blades of the right propeller on this Convair 340 separated in flight and one of them damaged the fuselage. |
| Event Time: | 1967-03-05 at 2007 EST |
| File Name: | 1967-03-05-US.pdf |
| Publishing Agency: | National Transportation Safety Board (NTSB) |
| Publishing Country: | USA |
| Report number: | NTSB-AAR-1968-02-26 |
| Pages: | 34 |
| Site of event: | Descent, near Marseilles, Ohio |
| Latitude/Longitude: | N40°41'25 W38°21'58" |
| Departure: | Columbus |
| Destination: | Toledo |
| Airplane Type(s): | ALLISON PROP-JET CONVAIR 340 |
| Flight Phase: | Cruise |
| Registration(s): | N73130 |
| Operator(s): | Lake Central Airlines |
| Type of flight: | Revenue |
| Occupants: | 38 |
| Fatalities: | 38 |
| Serious Injuries: | 0 |
| Minor/Non-Injured: | 0 |
| Other Injuries: | 0 |
| Executive Summary: | About 2007 EST, on March 5, 1967, Allison Prop-Jet Convair 340, N73130, being operated as Lake Central Airlines, Inc. Flight 527, crashed near Marseilles, Ohio. The 38 persons aboard the aircraft received fatal injuries. The aircraft was destroyed. Investigation revealed that all four blades of the right propeller separated in flight and the No. 2 blade penetrated the aircraft fuselage in line with the propeller plane. The penetrations destroyed the structural integrity of the fuselage to an extent that, together with the loads caused by a right yaw which accompanied the propeller separation, the fuselage failed along the line of penetrations and the aircraft crashed. Examination.of the internal mechanism of the right propeller revealed that the helical splines of the torque piston of the No. 3 blade pitch change unit were worn away and the torque cylinder was completely failed. The wear of the splines was due to an omission of nitriding for surface hardness during manufacture and the cylinder failure was caused by fatigue. When the torque cylinder failed, propeller oil pressure maintaining the pitch position of the right propeller blades was lost. The blades moved toward low pitch at a rate too rapid, for the propeller pitch lock to operate effectively. At a low blade angle the propeller oversped, causing the blades to separate in overstress. The Safety Board determines that the probable cause of this accident was the failure of the right propeller due to omission of the torque piston nitriding process during manufacture, and the failure of manufacturing quality control to detect the omission. |
| Learning Keywords: | Operations - Maintenance |
| Systems - Engine - Uncontained Engine Failure | |
| Other - Manufacturing Issues |
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