Appeal from the United States District Court for the Northern District of Illinois, Eastern Division. No. 75 C 764 -- Prentice H. Marshall, Judge.
Before Pell, Circuit Judge, PECK, Senior Circuit Judge,*fn* and Wood, Circuit Judge.
Plaintiff-appellant, Betty A. Campbell, Administrator of the estate of Jack E. Willeford, appeals from a final judgment entered on a jury verdict for the defendants in a wrongful death action. Federal jurisdiction is based on diversity of citizenship and the substantive law of Illinois is applicable.
The accident which caused Willeford's death occurred on May 12, 1974, at O'Hare Airport in Chicago, where the decedent was employed as a lead mechanic for Trans World Airlines (TWA).*fn1 On the day of the accident, Willeford was notified by the flight engineer of a departing Boeing stretch 727 that a strip of material was hanging from the rear stabilizer of the aircraft. Doubtless motivated by a desire to keep the flight on schedule, he drove immediately to the rear of the aircraft in a lift truck designed and manufactured by defendant Nordco Products (Nordco).
The lift truck is a maintenance vehicle with a hydraulic platform that can be extended up to thirty feet in height through the use of a set of double metal scissors. One of the safety features designed into the truck was a limit switch manufactured by defendant Micro Switch Company, a subsidiary of Honeywell, Inc. (Micro Switch). The purpose of the limit switch was to stop the platform at twelve feet if a set of four outrigger stabilizers had not been extended, because the vehicle, if not stabilized, was considered by Nordco to be unsafe above that height.
The stabilizers could be extended only through the controls at the side of the truck, and it was therefore impossible for a person on the platform to extend them from that position. Consequently the proper procedure in utilizing the lift required any mechanic who needed to work above a height of 12 feet to extend the stabilizers before mounting the platform.*fn2 The proper procedure, however, was not observed by Willeford for when he arrived below the tail of the aircraft, he immediately jumped on the platform and raised it to a height of approximately twenty-eight feet. The limit switch did not activate to halt the platform at twelve feet, and, as Willeford reached for the offending strip of material on the aircraft, the platform began to sway. He ran back to the controls in an attempt to lower the platform, but the vehicle continued to sway and ultimately fell. Willeford was killed when he jumped from the toppling vehicle and struck his head on the ground.
It was plaintiff's theory that Willeford was in a hurry when he drove to the aircraft, that he forgot to extend the stabilizers, and that the failure of the limit switch to stop the platform at twelve feet resulted from a design defect.
Plaintiff alleged that the design of the lift was unreasonably dangerous in one or more of the following respects: the limit switch was improperly installed; the design of the lift was such that the switch could become inoperative under normal working conditions; and an improper type of switch had been selected by the designer of the lift. Additionally, plaintiff contended that the design was unreasonably dangerous in that the outriggers did not extend automatically when the platform was raised, and that Nordco had failed to warn prospective operators that the vehicle could tip over under certain conditions.
Plaintiff's claims against Micro Switch were similar, specifically, that Micro Switch had provided an unreasonably dangerous product in that it had failed to instruct Nordco as to the proper method of installing the switch, or to warn Nordco that improper installation could cause the switch to become inoperative under normal conditions. The jury was instructed on all the above theories.
It was defendants' theory that Willeford knew the switch to be inoperative and assumed the risk in working above the twelve foot level without the stabilizers, that there was no defect in either the design of the lift or the method of installing the switch, and that the switch did not function because it had either intentionally or unintentionally been bent back after the product left Nordco's control.
The limit switch was installed at the rear of the platform and included a roller arm actuator mounted at a forty-five degree angle. As the platform moved upward, the roller shaft moved forward, striking the switch mechanism and causing the opening of a ground circuit through the downward movement of the actuator, thereby cutting the power and causing the platform to stop. Plaintiff contended, however, that the manner in which the switch had been installed caused the roller shaft to contact the mounting bracket on the back of the switch and bend it back to a point where the roller shaft could pass over the switch without the depression of the actuator necessary to break the circuit. There is no dispute that the switch was in fact found to be bent after the accident. Plaintiff's expert witness, Irving Hazard, was of the opinion that the specific cause of the bending was that the size of the screws used in mounting permitted clearance between the switch body and the bracket, thus allowing a slight rotation and bending of the mount with each passage of the bar.*fn3 In addition, Hazard testified that the safety of the design could have been improved by the selection of a different type of switch.*fn4
Defendant's expert witness, Professor Ralph Barnett, disagreed with all of the above assertions. With respect to the method of installation, Professor Barnett testified first that the screws and bolts used to mount the switch were of the proper size and that the calculations of plaintiff's expert witness contained an arithmetical error. He also testified that the switch was mounted in an optimal location, and that it was virtually immovable due to the fact that it had been mounted on a heavy steel bracket and welded into place. He disagreed that the bending of the bracket could have been caused by the passage of the roller bar and was rather of the opinion that the switch had been forced back by some type of lever, e. g., a heavy screwdriver. In support of this opinion, he pointed out the presence of scratch marks on the brass coating of the bracket, and testified that he had conducted experiments in a laboratory, whereby he had deliberately bent several switches, and had produced scratch marks similar to those on the switch involved in the accident.
Finally, Professor Barnett disagreed that the design of the lift was unreasonably dangerous in that the stabilizers did not extend automatically when the platform was raised. While acknowledging that this design modification was effected by Nordco after the accident that caused Willeford's death, he opined that the original design was preferable from the standpoint of both safety and efficiency. First, the fact that the lift could be operated at heights up to twelve feet without the stabilizers permitted mechanics working at those heights to get closer to their work. Secondly, Professor Barnett noted that with the modified design, the stabilizers extended immediately upon the mechanic's pushing the "Platform Raise" button, which created a risk in that a mechanic not thoroughly trained on the operation of the lift might press the button without being aware ...