Opinion ID: 1146481
Heading Depth: 1
Heading Rank: 3

Heading: Magneto Settings

Text: In passing to a consideration of the matter of magneto settings, we begin by saying Continental engineers were of the opinion  when the company answered interrogatories for Joly and throughout the trial  that the cause of the failure of Piston 3 was pre-ignition. However, we must not lose sight of the fact that Continental does not have the burden of proving what caused such failure. It is clearly the responsibility and burden of the claimants to show by substantial evidence what caused the plane to go down. As to what caused the accident, it has been conclusively decided that improper maintenance on the part of Wyoming Air Service was a cause. Our question now is whether Joly and Darr have proved there was another cause  one chargeable to Continental. If so, it has to be in connection with magneto settings. Joly and Darr claim the proper setting for both magnetos on the engine owned by Darr was 20° B.T.C.; and that the engine in Darr's plane had the magnetos set at 24° B.T.C. when it left the manufacturer. As proof of this, there was offered in evidence a bulletin from Continental to all its distributors, dealers, repair and overhaul agencies, engine owners and operators dated February 7, 1962. This bulletin stressed the importance of establishing and maintaining correct magneto timing. Attached to the bulletin for quick reference was a listing of the correct magneto timing settings for all Continental engine models. The setting for the model we are concerned with was shown on the attachment to be 20° for both magnetos. Darr's plane was manufactured in 1962. The Log of Engine Test shows the standard acceptance test was February 20, 1962. The Aircraft Log shows that it was certified by FAA for airworthiness on May 17, 1962. It is undisputed that the plane came out with both magnetos set at 24° B.T.C. Thus, on the face of the exhibit dated February 7, 1962, it would appear the plane came out with the magnetos set 4° higher than what was recommended. The explanation offered by Continental's engineer who was responsible for the bulletin was that a 24° setting is the optimum setting for this engine; that such setting produces the greatest horse power and the most efficient operation of the engine. However, from tests on airplane engines and despite constant warnings to make sure magnetos are properly set at each 100-hour inspection, Continental found the normal advance of magnetos was not being corrected to the specified setting by repair and overhaul agencies. Thus, according to Continental's testimony, the company determined that the engine could take a small drop in horsepower by altering the magneto setting to 20°, thereby building in some slack as protection for the engine as the magnetos advanced. It is undisputed that, to accomplish such a change, it is always necessary to obtain FAA approval, just as it is necessary to have original specifications approved when the engine is first designed. There are a number of Continental bulletins in evidence. They show the company had been giving repeated warnings about keeping the magneto settings checked and at the proper place. They also show, despite such warnings, engines were being damaged because of failure on the part of service personnel to keep the magnetos where they should be. According to the explanation of Continental's engineer who was responsible for this matter, the February 7, 1962, bulletin was put out when 24° was still the FAA approved setting for magnetos on the engine with which we are concerned; and the attachment originally attached to the February 7 bulletin showed the correct setting for this engine to be 24°. The witness testified 24° was still the approved setting when this engine was turned out. It was after that, in fact in June, 1962, he said, when the change to 20° was approved. According to the explanation of the witness, the body of the February 7 bulletin was not then changed but the original attachment was removed and a new one attached in its place. The new attachment showed the correct setting as 20°. The exhibit offered by claimants, as Continental explains it, has the original date of February 7, 1962, and the substituted attachment which was affixed after FAA approval in June 1962. Except for the exhibit introduced by plaintiff, with the 20° attachment, there was no contradiction in the evidence of Continental's testimony that 24° was in reality the optimum setting for Darr's engine and that the engine would produce the greatest horsepower and operate most efficiently at 24°. There is also no contradiction of the company's explanation that a change was actually approved by FAA in June 1962, and that the attachment to the February 7 bulletin was then changed. There is then no dispute of Continental's explanation that, when Darr's engine left the factory, the attachment to the February 7 bulletin showed 24° as the correct magneto setting. Several bulletins issued by Continental to its dealers, owners, operators, and repair and servicing agencies were introduced in evidence. In these bulletins the importance of maintaining proper magneto timing was stressed. For example, a bulletin dated December 10, 1959, stated: With today's high performance engines, correct magneto timing is a matter of utmost importance. Magneto timing in advance of specified settings can cause detonation and even destructive pre-ignition resulting in broken piston rings, cylinder scoring and piston burning. Also, in the bulletin dated February 7, 1962, which claimants rely on so strongly, this pertinent language was contained: The importance of establishing and maintaining correct magneto timing on today's high performance engines cannot be over-emphasized. A continuing survey of magneto timing reflects a finding of 50 percent of the engines checked having magneto timing set in advance (some as much as 20°) of the setting specified for the engine. These advanced timing settings are believed in some cases to be the result of the erroneous practice of bumping magnetos up in timing in order to reduce RPM drop on single ignition. NEVER ADVANCE TIMING BEYOND SPECIFICATIONS IN ORDER TO REDUCE RPM DROP. We believe that perhaps too much importance is being attached to RPM drop in single ignition. RPM drop on single ignition is a natural characteristic of dual ignition design in modern engines. The purpose of the magneto check is to determine that all cylinders are firing. If all cylinders are not firing, the engine will run extremely rough and cause for investigation will be quite apparent.    It is important to notice that in these bulletins the company was talking about an alarmingly high percentage of cases where timing was advanced far beyond specified settings. It emphasized the importance of magneto timing check and readjustment as required at each 100-hour inspection. And particularly, in the February 7, 1962, bulletin, the company pointed out that 50 percent of the engines checked were being found to have magneto timing set in advance of the specified setting  some as much as 20° above. Witnesses for Continental testified magneto settings, with wear and use of an engine, have a tendency to change; and this is the reason that it is considered one of the things to be examined on each 100-hour inspection. If this were not so, there would be no need to reset or recheck. Also, one of the witnesses described how the company was continually finding magnetos advanced. Because this engine was fat in power, the witness testified, the company decided it could take about one and a half horsepower drop in power from the optimum and take the four-degree-cushion to aid in this problem. There is no dispute or contradiction in the evidence of Continental's testimony concerning the optimum setting for the engine model in question, nor concerning reasons for changing the recommended setting from 24° to 20°. Also, there is no dispute or contradiction in the evidence of those things claimed by Continental in its bulletins. This includes such claims as a finding that 50 percent of the engines checked had magneto timing set in advance of the specified setting; that there was an alarmingly high percentage of cases where the setting was far beyond specified settings; that some of these settings were as much as 20° above the proper setting; that the advanced timing settings are believed in some cases to be the result of the erroneous practice of bumping magnetos up in timing to reduce RPM drop; that the purpose of the magneto check is to determine that all cylinders are firing and if all cylinders are not firing, the engine will run extremely rough and cause for investigation will be quite apparent. It might be worth calling attention at this point to the fact that Joly reported engine roughness on a flight from Minnesota. Then, on the day of his ill-fated trip, he set his plane down at Riverton for servicing after flying only from Lander to Riverton (about 25 miles), with a report that the engine was rough.