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On April 9, 1963, the FAA held a meeting with Standard in order to rectify deficiencies in the company's maintenance program. Items for discussion in the category of maintenance records included component serial numbers, TSO times, and missing cards for aircraft components. It was agreed at this meeting that a closer monitoring of logbooks and maintenance records was needed. It was also agreed that the FAA would continue with the inspection of Standard‘s records and maintenance manuals and that the company would make the necessary revisions and corrections as soon as possible. The completion date of this project was not to exceed May 27, 1963; however, as of the date of the accident it had not been completed. It may be well to note that following the accident and during the period the accident investigation was in process, six additional aircraft were certificated by the FAA and were incorporated into Standard‘s aircraft fleet.
On June 3, 1963, six days after the Manhattan, Kansas, accident, another Standard Airways, L-1049G, N 9742Z, experienced a propeller malfunction in flight. The captain of the flight stated that while cruising at 9,000 feet in the vicinity of Elkins, West Virginia, the No. 2 propeller surged twice from 2300 to 2800 r.p.m. Attempts to control the propeller through the use of the manual propeller control switch were unsuccessful. The propeller was then feathered and the flight continued to Philadelphia and landed without further difficulty. After landing, the No. 2 propeller was unfeathered and during ground run-up the propeller inadvertently went into reverse pitch.
On examination of the No. 2 propeller assembly the spinner was removed and the power unit (S/N 168011) brake cage was found completely unscrewed lying loose inside. The two cage lock safety bolts were missing from the unit and two of the brake cage locking bolt slots were worn excessively. The outer periphery of the splined disc duplex brake plate assembly was peened for approximately 180 degrees. The brake lining was well within limits. A part of a bolt, similar in appearance to the specified brake cage locking bolt (P/N 106024), was found on the ground under the engine. This portion of the bolt was examined and found to be within the manufacturer's metallurgical design specification tolerances. The threaded brake cage was reinstalled to the locked position and the brake clearance was found to be .011 inches. The power unit was energized and normal propeller operation was obtained.
It is to be noted that on May 29, 1963, both the CAB and the FAA contacted Standard Airways, and requested that the propeller power units on N 9742Z be inspected "as soon as possible" regarding the possibilities of a similar propeller malfunction. The crew of N 9742Z stated they had been advised by the company of the accident at Manhattan but did not receive specific information as to the nature of the propeller malfunction. Moreover, it was stated that no instructions were received from the company to inspect the propellers or power units on N 9742Z prior to the incident on June 3, 1963.
Analysis
Examination of the No. 3 propeller assembly revealed an impact blade angle of plus one-degree, this is 22.7 degrees below the specified low blade angle setting and in the reverse pitch range. The threaded brake cage locking bolts were missing and the cage had unscrewed three threads. This resulted in an
