During the course of my investigation of United Flight 823, I have made several attempts to obtain testimony given during the Public Hearing that took place in Knoxville, Tennessee from January 12 until January 16, 1965. The different inquiries that I have made have received the same response: “The requested documents can not be found”.
One document that I do have in my possession was authored in March, 1966. It is a recommendation sent to the Civil Aeronautics Board by attorneys for United Airlines. The document is twenty-six pages long. It mentions various testimonies given at the Public Hearing that took place in Knoxville, as well as a deposition that took place in Washington, D.C. on November 3-4, 1965.
The document is very helpful in that it refers to testimony that was given during the hearings and brings to light testimony that differs from the conclusions found in the final Civil Aeronautics Board report-the most important of which was contrary testimony provided by the Bureau of Safety which United Airlines claims to be a “major point of dispute”.
The Bureau of Safety, at that time, was part of the Civil Aeronautics Board.
According to the United Airlines, one of the major points of dispute had to do with a claim made by the Bureau of Safety that a battery cable had become disengaged and struck a hydraulic line and produced an arc that ignited hydraulic fluid.
The following is from Page 10 of the United Airlines March 1966 report to the CAB: “The only other point within the electrical compartment that could even be remotely considered as a source of ignition between the hydraulic lines and an electrical component is the area on the starboard side below the Sonotone batteries. There was a vague intimation during the course of the investigation and hearing that perhaps one of the battery connector cables became disengaged, fell and struck a hydraulic line, broke the line, and produced an arc which ignited the hydraulic fluid emanating from the broken line. This theory was put to rest by witness Bannister (Note by TD: G.T. Bannister was an employee of the British Aircraft Corporation). Mr. Bannister pointed out that, as the hydraulic lines pass below the battery boxes, they are shielded by a protective channel composed of Marco Board. Furthermore, the construction of the battery connectors is such that the metallic elements are encased in a rugged phenolic unit which renders it impossible to come into contact with the metallic hydraulic lines. This phenolic material is an extremely strong substance and would certainly have withstood the small force that would be generated by a fall from the battery to the Marco Board below it.”
While much rationale can be attributed to the above explanation presented by United Airlines, one is still left to wonder if any of the investigating authorities were ever aware of the potential, volatile nature of the Marathon Sonotone Nickel Cadmium batteries and contributing factors that could have led to thermal runaway of the batteries on board United Flight 823.
Two factors lead me to believe that there was a lack of awareness, during the investigation of Flight 823, of the danger posed by Marathon Sonotone batteries.
First, there was no corrective action taken with regard to nickel cadmium batteries until after the Aloha Airlines Flight 845 accident on the runway in Honolulu that took place on August 8, 1971. The corrective action taken as a result of that accident was included in Airworthiness Directive 71-21-5 and Advisory Circular AC 00-33. These were superseded by Advisory Circular AC 00-33A, dated February 14, 1973.
Second, the information regarding Sonotone batteries that I have found in United Airlines and Capital Airlines flight manuals from the early 1960s do not mention dangers or risks involved with the use of Sonotone batteries in Vickers Viscount aircraft. In fact, it is my opinion that the Airworthiness Directives and Advisory Circulars directly contradict the information provided in the aforementioned flight manuals and show how a false sense of security was made possible with regard to Sonotone batteries.
UPDATE: Correction. An ORDER from the FAA, dated, 8/8/66 was issued with regard to nickel cadmium batteries. This bulletin included a discussion of tests performed on ni-cad batteries and methods used to charge them. Corrections via Airworthiness Directive 71-21-5 concerned the different types of battery cases that comprised Sonotone Batteries and their tendency to overheat, while the later Advisory Circulars were refinements of the FAA Order of 1966.