AVIATION SAFETY FRIDAY, FEBRUARY 15, 1952 HOUSE OF REPRESENTATIVES, SUBCOMMITTEE OF THE COMMITTEE ON INTERSTATE AND FOREIGN COMMERCE, Washington, D. C. The subcommittee met at 2 p. m., Hon. Lindley Beckworth (chairman) presiding. Mr. BECKWORTH. The committee will please be in order. When we adjourned on yesterday the chairman was testifying. It is my understanding Mr. Hinshaw has some questions he wishes to ask about some accidents that occurred to the C-46's. If you will take the stand, Mr. Hinshaw will ask you some questions. STATEMENT OF JOHN M. CHAMBERLAIN-Resumed Mr. HINSHAW. On yesterday, Mr. Chamberlain, in the course of discussing accidents that had occurred to C-46 aircraft, you mentioned that there were a few accidents or several accidents-I do not remember which-which had occurred to C-46 aircraft as the result of the failure of one engine. I wish, Mr. Chamberlain, you would give us a brief statement about those accidents; how many there were, and so forth; and the relationship that that number bears to the total number of serious C-46 accidents, and any other information which you have. Mr. CHAMBERLAIN. Mr. Chairman, I have several documents here in the form of accident statistics which were furnished me this morning by Mr. Andrews, Director, Bureau of Safety Investigation, which material I believe has been available heretofore. The one document here is entitled, "Summary of C-46 Accidents Which Involve Inability to Maintain Altitude on Single Engine Following Engine Failure During Takeoff Climb." That is dated October 1, 1951, and was prepared by the Bureau of Safety Investigation of the Board, I believe at that time to be introduced as factual evidence in the Board's public hearing in connection with the proposed rule making for the C-46 airplane. This covers nine accidents some of which there have been formal board reports issued on and others which are merely based on the evidence in the Board's accident investigation records. In those cases there are no conclusions drawn in this report. This is merely a very brief presentation of factual evidence and if you wish me to read this in detail, I shall. Mr. HINSHAW. Mr. Chairman, in view of the fact that the committee does not have individual copies of this document for its own perusal and in view of the importance of the matter, I think it well that the gentleman read it, if that is the pleasure of the committee. Mr. BECKWORTH. You may proceed to read it, Mr. Chamberlain. Mr. CHAMBERLAIN. Incidentally, we can furnish additional copies of this if the committee wishes, a t a later time. It is as follows: ACCIDENT No. 1 This accident occurred at Asmara, Eritrea, Africa, on January 26, 1949 (Alaska Airlines). Acceleration and power was normal until gear was retracted, at which time the right engine power dropped to about 70 percent and continued dropping as flight continued. Air speed dropped from 95 to 80 miles per hour. In an effort to remain airborne, estimated altitude 50 to 75 feet, flight was sustained with full throttle setting and full r. p. m. on both engines-No. 1 was putting out 50 to 70 percent of its power. After completing about 270 degree turn, runway 120 degrees was located, gear was dropped 10 seconds before contact with the ground some 200 feet short of the field on a heading of about 090 degrees. Runway length_ Weight on take-off. _feet__ 6, 300 __do_____ 7,628 -pounds-- 42, 250 "NOTE.-CAA report states that there was some question as to whether aircraft was overloaded in view of the 7,628 feet elevation. The airplane manual does not cover performance specifications above 6,000 feet or loads less than 45,000 pounds. The determination as to whether the aircraft was overloaded or not could not be determined at Asmara, according to the CAA report. Asmara at the time was the main service base for Alaska Airlines operations, Aden to Lydon. Maintenance superintendent reported that engines were in "top shape." A No. 1 check had been accomplished 5 hours flying time prior to the accident, and it was stated that preflight inspection was made the evening prior to this flight; and that both airframe and engine time were low. Engines were checked following accident. Main fuel screens were removed and found clean. The carburetor fuel screen was removed and found to contain what was believed to be chamois lint. ACCIDENT No. 2 This accident occurred at Seattle, Wash., on July 19, 1949 (Air Transport Associates.) The aircraft rolled some 3,500 feet down runway 31 (7,500 feet long), then became airborne at an air speed of 105 miles per hour. During the run, one of the engines was heard to sputter and backfire, and an unusual amount of torching or exhaust flame was observed coming from both of the engines. Because the left engine did not seem to be developing full power, the captain, at an altitude of some 20 feet retarded the throttles and the aircraft settled back to the runway. At the time of the accident the green threshold lights at the north end of the runway (31) had been moved in 1,700 feet for runway repair purposes, in effect reducing the length of the runway to 5,800 feet. However, this north portion of the runway was usable for take-off. After touching down on the runway, approximately 4,500 feet from the start of the take-off and 1,300 feet from the green threshold lights, the captain did not believe that he had sufficient runway to accomplish a safe stop, so he advanced the throttles to the limit of 52 inches, both engines responded, but the left continued to misfire. After a momentary ground roll the aircraft again became airborne at an air speed of 105 miles per hour. Landing gear was retracted, air speed increased slowly to approximately 110 miles per hour, and the flight continued over the north end of the runway at about 50 feet above the ground in a nose high attitude. Sufficient altitude could not be obtained to fly over power lines and poles to the north of the airport, and 1,500 feet north of runway 31 the aircraft struck a 56-foot pole two feet below its top. A second pole, 1,480 feet from the first, was struck, then a third pole 200 feet from the second. As a result, air speed and altitude were lost, and 200 feet from the third pole the aircraft crashed into a three-story house. Investigation disclosed, among other things, that 91 octane fuel was used for run-up on the ground and for the take-off with the engines operating on the front main tanks. The aircraft was certificated under a specification which provided only for the use of fuel of 100 octane rating or above. The probable cause of this accident was determined to be the indecision of the pilot in continuing a take-off after loss of power in the left engine, which loss was probably caused by the use of 91 octane fuel, necessitating the operation of the aircraft's engines in excess of the approved operating limitations. Crashed in the Atlantic Ocean 6.4 statute miles west of Isle Grande Airport, San Juan, P. R. (Strato Freight, Inc.) Of the 75 passengers and crew of six aboard, 52 passengers and one crew member lost their lives. Weight on take-off. Allowable limits. Pounds 48, 709 45,000 3,709 One minute after the aircraft left the ground, and at an indicated air speed of approximately 115 miles per hour and at an indicated altitude of 250 feet, mean sea level, the right engine began to backfire severely and lose power. No attempt was made to feather the right engine. An emergency was declared, and the tower cleared the flight to land on runway 9. But, since air speed was low and altitude could not be maintained, the aircraft was flown straight ahead for a crash landing 200 yards off the shore at Punta Salinas. Disassembly of the right engine disclosed, among other things, that 30 of the 36 spark plugs were type AC-LS-87 spark plugs which were not approved by the manufacturer of the engines, or by the United States Air Force, for use in the engines which were installed in this aircraft. Furthermore, the spark plug terminals for this engine were found to be oily and dirty and spark plug electrodes were found to have too much clearance. Following failure of the right engine, the aircraft failed to remain airborne despite the fact that the left engine was apparently developing full power, because the aircraft did not have single engine climb speed and its gross load was 3,709 pounds more than the certificated weight. Other factors contributed to this lack of single engine performance; the right propeller was not feathered, and the right cowl flaps were fully opened and the landing lights were extended, all of which would materially increase the parasitic and interference drag. The probable cause of this accident was the loss of power of the right engine before the aircraft attained the optimum single engine climb speed which, together with the overloaded conditions of the aircraft, resulted in its losing altitude and falling into the sea. Mr. WOLVERTON. Was there any reference in that report to the type of gasoline? Mr. CHAMBERLAIN. I believe not, sir. It refers to the improper gasoline in the preceding accident. There was none in this one. ACCIDENT No. 4 Crashed about one-half mile from the Teterboro, N. J., airport shortly after take-off on May 27, 1950 (Regina Cargo Airlines). The captain was fatally injured and the copilot received serious injuries. Weight on take-off__ Allowable limits- Excess Runway length__-. - 50,076 pounds 45, 000 pounds 5,076 pounds 4,500 feet At an altitude of some 200 to 300 feet mean sea level, the left engine started to misfire. The landing gear had been raised and was checked for position. The left engine continued misfiring and shortly became worse. The left propeller was feathered. Full power was maintained on the right engine and a left turn was started as if to return to the airport. At this point the altitude was estimated to be 400 to 500 feet. During the turn the air speed fell to 85 to 90 miles per hour and the aircraft settled. This turning continued until the aircraft neared the ground, when it was leveled laterally. It struck while about level. Upon inspection, the ignition system of the left engine showed abnormalities. The spark plugs of this and of the right engine were of an approved type for this model engine. Four of the 36 spark plugs of the left engine proved defective inasmuch as they fired either irregularly or not at all when tested in the condition in which they were removed from the engine. Furthermore, five other spark plugs exceeded the specified limits when tested for gas leakage. Company records indicated that these spark plugs had been in service for 92 hours and 55 minutes, which is 67 hours and 5 minutes less than the maximum allowable amount. Examination of the right engine disclosed a number of ignition abnormalities but to a lesser degree than in the left engine. The best single-engine speed of the aircraft, with a maximum gross weight of 45,000 pounds, according to company's operations manual, is 125 miles per hour. At a gross weight of 50,000 pounds, this speed would be somewhat increased. At the time the left engine malfunctioned and was feathered, the air speed had reached an estimated 130 to 135 miles per hour. The sustained misfiring of the left engine and the subsequent feathering appears to have resulted from the additive effects of three factors: (1) the condition of the spark plugs, the abnormally wide range in the gaps of the spark plug electrodes which indicate that the plugs had been improperly gapped. and thus excessive erosion occurred prior to the normal replacement period of 160 hours; (2) the condition of the magnetos-the breaker points of both magnetos were burned and oily and the magnetos were improperly timed. (Thus, it is evident that both of these accessories were in a poor state of maintenance. Their accumulative effect apparently caused irregular firing.); (3) under takeoff conditions when manifold pressure was greater than that used during the run-up, as is normally the case, this misfiring would become more accentuated. As far as the right engine is concerned, there is no evidence to indicate any power interruption from the time of take-off until the crash, although its condition indicated marginal maintenance. Probable cause: Overloading of the aircraft due to faulty loading and dispatch procedures, coupled with engine malfunctioning due to inadequate maintenance. ACCIDENT No. 5 Preliminary data only available at this time. Accident occurred at Chicago, Ill., on September 16, 1951 (Peninsular Air Transport). Left engine backfired and lost power during take-off-altitude some 200 feet and air speed about 105 miles per hour-propeller was feathered. Unable to maintain altitude on one engine. Investigation disclosed insufficient number of threads in the spark plug bushing to hold the newly installed plug properly. Also due to erosion a leak existed which caused overheating of the plug. The plug points fuzed and pre-ignition occurred. Preliminary evidence indicates that the aircraft was overloaded by some 1,000 pounds. Summary of take-off accidents: No engine failure. Mr. HINSHAW. That is five accidents on account of engine failure? Mr. CHAMBERLAIN. That is right. Mr. HINSHAW. The next are a result of what? Mr. CHAMBERLAIN (reading). "Summary of Take-off Accidents— No Engine Failure." I am sorry; when I read the title I thought it referred to the nine accidents. The five accidents I have just read involve engine failure sometime during the take-off or in the ensuing climb. The following ones apparently involve no engine failure. ACCIDENT No. 6 This occurred on September 30, 1948, at Basra, Iraq, and involved Skyways International Trading & Transport Co., Inc. Failed to become airborne, no engine failure. Weight on take-off_ Allowable limits__. Runway length_ -pounds__ 40, 040 ----do‒‒‒‒ 45,000 --feet 6,000 Incidentally, do you wish me to continue with these, even though they do not involve engine failures? Mr. HINSHAW. It would be interesting to know what caused the failure. Mr. CHAMBERLAIN (reading): Take-off made in hot, still air conditions. Inadequate flight preparations, and inadequate maintenance. Primary cause of accident stated to be misuse of brakes and flight controls on ground. I might add at this point that this is very brief. Obviously it was not an accident that was investigated, due to the location and the relative importance of this particular one. ACCIDENT No. 7 This accident occurred on July 30, 1950, at Denver, Colo. (Flying Tiger Line). Calm conditions. Left ground, settled back in, then became airborne within few feet of runway end, and then struck a power-line pole, 1,900 feet from end of runway. Weight on take-off. Allowable limits-- 47, 172 pounds. 48, 000 pounds. 172 pounds. There is a parenthetical expression there saying "At least"; apparently there was some question of the precise weight. Mr. HINSHAW. Let us get down to that case. You had five-thousandsome-odd feet of altitude at that point? Mr. CHAMBERLAIN. That is correct. Mr. HINSHAW. How do you figure 48,000 pounds allowable takeoff weight, when that is the maximum? Mr. CHAMBERLAIN. This apparently is a cargo flight, and the requirements do not prescribe a corresponding reduction in weight with an increase in elevation of take-off area for cargo-type operation. I mentioned yesterday, I believe, that the transport category requirements, which apply to passenger operation, do prescribe such a reduction. It was not applicable in this case, however. Mr. HINSHAW. Go ahead. Mr. CHAMBERLAIN (reading): Runway length_. 6,980 feet. 5, 325 ASL. 6,500 feet. Information contained in the CAA-approved flight manual for this model aircraft shows that, under the weight conditions, noted above and at the density altitude of 6,500 feet which existed at time of take-off, the aircraft should have attained an altitude of 50 feet and an air speed of 1231⁄2 miles per hour after traversing a distance of approximately 5,850 feet from the start of its take-off run. The runway (No. 17) at this airport (Stapleton) has a slight uphill gradient, the south end being 40 feet higher than the north end. This gradient would normally lengthen the take-off run by 320 feet, assuming that the aircraft became airborne at 95 miles per hour and the gradient was uniform. However, since the aircraft accelerated to an air speed of only 90 to 100 miles per hour and was pulled off the ground just before it reached the end of the 6,980 feet runway, it is apparent on the basis of these figures that the take-off was subnormal due to an increase over the normal drag in the take-off configuration, or to a loss of thrust horsepower, or to a combination of the two. The pilot of this plane stated that it was consistently slower in accelerating and taking off than any other aircraft of the same type that he had flown. Investigation disclosed, among other things, no evidence to indicate any loss of thrust horsepower due either to the propellers not being in low-pitch position or to the malfunction of the power plants. An examination of the engines and propeller disclosed no defects which could have resulted in any substantial loss of power and the crew members stated that the engines operated normally at 2,700 r. p. m. and 45 inches of manifold pressure at take-off. |