wr. George Sn Moore (2)
The Bureau‘s investigation of the flight log records of C—héF, N67935 revealed several incidents of maintenance practices which are not in our opinion conducive to acceptable standards of airworthiness. On August 15, 1953, at Albuquerque, New Mexico, the left magneto and both distributor fingers of the right engine were replaced by a military mechanic without appropriate FAA ratings. The approval of this work was not certified until the completion of a Logair flight to Ogden, Utah, the same date. The flight logs of N67935 for a period between August 3, 1963 to September 21, 1963, covering 14 flights, revealed that the aircraft was operated with the oil pressure of the left engine at 50 psi which is below specified limits. Corrective action was taken on five of the flights; however, it did not correct the problem.
Our investigation of the maintenance facilities of Aaxico Airlines at Oakland, California, revealed that the carrier had experienced eleven R-2800B series engine failures between the period of July 1, 1963 to September 19, 1963. we believe that this number of failures is high for a fleet of 12 C-46 aircraft. At the time of the Board's investigation, and to this date, the causes of all of these failures are unknown; however, four of the failures resulted from failure of the P/N hh76h exhaust valve.
The Bureau is aware that the P/N hh76h valVe is an obsolete type and that improved types are available. we are also aware that some operators and overhaul agencies are using the newer type valves which assure setter service life.
In view of the questionable maintenance practices of Aaxico Airlines, it is recommended that a review of the maintenance and inspection practices and procedures of this carrier be reviewed and improvements be made where necessary in order that acceptable airworthiness standards are assured. It is also suggested that consideration be given to time limiting P/N hhTSh exhaust valves for use on C-46 series aircraft.
During investigation of these accidents, personnel of our Engineering Division discussed these findings with Messrs. K. E. Neland, J. J. Morris and J. Haddad of your Flight Standards Service and J. Kiselica, Flight Standards Division, Eastern Region.
If we can be of any further assistance in your consideration of these recommendations, please feel free to contact us.
Sincerely yours,
/s/ Leon H. Tanguay Director, Bureau of Safety
