control, such as an engine surge at time of failure, may have been responsible for the indication of overstretch. In any event at the very best the evidence is in equipoise.
The fact the cause of overstretching, if any, could not be determined does not, of course, end the matter. It is necessary to consider whether the accident would not have occurred if shot-peened bolts and chrome-backed bearings had been installed in Juneau III's sixth cylinder, that is, whether the failure to comply with the service bulletins and the subsequent FAA directive was a proximate cause of the engine failure and resulting crash.
The engine originally had chrome-backed bearings. Because the service bulletins were confusing, Saguaro communicated with Avco to determine whether plain or chrome-backed bearings should be used at time of overhaul. Bearings are not part of the rod assembly and a pertinent service bulletin, #1184A, did not indicate which type of bearing to use. Saguaro was incorrectly advised by Avco it could use plain bearings and used plain bearings it had in stock. In the certified parts list which accompanied the engine after overhaul it gave notice it had installed bearings that were not chrome backed.
It is a known phenomenon that galling of bearings can lead to a buildup which will cause the rod to fail at several different possible points, including the bolts. The bearings in the sixth cylinder were chewed up as a result of the failure and could not be analyzed. There is no proof that they caused the rod-bolt failure. Bearings in the other cylinders were generally in good condition, only a few showing very minor indications of incipient galling.
Turning to the effect of shot-peening on the life of a bolt subject to stress, the proof was more concrete. Commencing in the late 1960's it was recognized by Avco and others that tear and subsequent wear could occur on the connecting rod bolts as they loosened due to stress or other factors and cause bolt fatigue and failure at a point of fretting or galling. Indeed, a number of helicopter engines had failed due to bolt fatigue. Avco, in its constant commendable effort to improve engine reliability and life, developed a shot-peened bolt which had distinct advantages. This bolt, by a slight dimpling effect, retains lubrication and lessens wear as a bolt gradually fatigues following fretting or galling. Avco's chief engineer indicated that shot-peening would extend bolt life once fatigue set in by up to 20 hours. In all other respects the shot-peened bolt has the same strength, hardness and operational characteristics as a nonshot-peened bolt. Thus it is apparent that if Juneau III's engine had had shot-peened connecting rod bolts the helicopter would not have crashed when it did.
II. CONCLUSIONS OF LAW
Those who build aircraft and component parts to be used for general aviation purposes must be held to high standards. It is essential that these concerns as well as aircraft operators be ever conscious that a plane is an inherently dangerous and sensitive instrumentality which can cause great harm if high standards of care are relaxed. The complex and exacting scheme of regulation developed by the FAA to this end must be reinforced and strengthened by courts called on to develop rules of liability and damages in situations like the instant case where it is apparent that high standards consistent with the regulatory scheme have not been maintained with resulting injury to persons and property. Given this premise and in light of the facts detailed above, legal conclusions as to liability must now be set forth.
It will be recalled that the bolt which broke and caused the accident showed a fatigue crack one-third through its diameter and that shot-peening would prolong the life of the bolt up to 20 hours after fatigue had occurred. There was no proof indicating the length of time shot-peening would serve to delay the beginning of a crack caused by fretting or galling. It is apparent that if the required #77450 assembly had been installed, shot-peened bolts would have been installed and the engine failure would not have occurred when it did or earlier. Avco's engineering department revised its controlling drawing for this rod assembly to show use of shot-peened designed bolts in the connecting rod assembly as early as February, 1972, at which time this engineering improvement was approved by the FAA. A proximate cause of the engine failure was Avco's negligent failure to differentiate between a #77450 assembly without shot-peened bolts, which it caused to be installed at the last major overhaul of Juneau III's engine, and a #77450 assembly with shot-peened bolts, as required by the FAA directive and related service bulletins. Saguaro bears no responsibility, for it used parts approved by Avco and the overhaul was properly performed in all respects.
In spite of Avco's negligence in this regard, however, the District's claim against defendant for negligence must fail because of its contributory negligence, which arose out of inattention but not by reason of any malicious or criminal conduct. An engine log entry of December 23, 1972, at a time when the District was both owner and operator and after 303D had issued, states:
Top OH (overhaul) this date at 596.4. Replaced all exhaust valves and number six cylinder guide, rings, gaskets, and seals as required. Total time since major overhaul 596.4. Engine installed by (unintelligible).
In other words, the engine was removed by the District, taken apart and full opportunity existed for its mechanics to determine with ease whether or not the engine was in compliance with 303D. This was not done.
Moreover, as the testimony at trial indicated, the District, as a matter of law, had the primary responsibility as owner-operator to comply with the FAA's mandatory directive when it issued in February. See also 14 C.F.R. § 39.3 (1975). An adequate examination of Saguaro's parts list would have shown that the engine was not in compliance as to the bearings. It is a fair inference that if the bearings had been changed the absence of shot-peened bolts in the rods would have been noted and corrected. Thus, had the parts list been adequately checked by the District at the time the FAA mandatory directive issued, the accident would not have occurred, and a clear duty rested on the District to see that the directive was followed.
Fisher's claim against Avco is not barred by the negligence of the District. The law in this Circuit is well settled "by innumerable authorities that if, injury be caused by the concurring negligence of the defendant and a third person, the defendant is liable to the same extent as though it had been caused by his negligence alone. 'It is no defense for a wrongdoer that a third party shared the guilt of the same wrongful act, nor can he escape liability for the damages he has caused on the ground that the wrongful act of a third party contributed to the injury.' Choctaw, O. & G. R. Co. v. Holloway, [8 Cir.] 114 F. 458, [461-] 462 [ aff'd, 191 U.S. 334, 24 S. Ct. 102, 48 L. Ed. 207 (1903)]." Miller v. Union Pacific R. Co., 290 U.S. 227, 236, 54 S. Ct. 172, 174, 78 L. Ed. 285 (1933). See Hicks v. United States, 167 U.S.App.D.C. 169, 511 F.2d 407, 420-21 1975; Danzansky v. Zimbolist, 70 App.D.C. 234, 105 F.2d 457, 459 (1939); Campbell v. District of Columbia, 64 App.D.C. 375, 78 F.2d 725, 726-27 (1935). There is absolutely nothing in this record to suggest that the action or inaction of the District was malicious or criminal. See W. Prosser, Law of Torts § 44, at 287 (4th ed. 1971). Since a helicopter is a dangerous instrumentality, e.g., Middlleton v. United Aircraft Corp., 204 F. Supp. 856 (S.D.N.Y. 1960), the observations of the Second Circuit in a closely analogous case are particularly pertinent here:
Plaintiff's expert witness testified that the crack in the skid iron, at the place where it sheared off or broke at the time of the accident, was a progressive crack and must have had its inception a considerable time before the final and complete severance. He also testified that the crack should have been visible to the naked eye from the side, though not across the surface of the metal on the inside of the right-angled bend. There was evidence that McGrath subjected all of its equipment to monthly inspection, but the crack was not observed, or reported.
It is elementary that the concurrent negligence of some third person will not absolve a defendant upon whom liability is sought to be imposed for the consequences of his own delict. Could the jury here, on the evidence before it, have properly found that the flow of causation, arising from the negligent fabrication of the skid iron by Farrington, was broken by McGrath's failure to discover the defect?