Generally, aviators don’t like surprises. The good ones—like catching an unexpected 30-knot tailwind, or finding an ANR headset under the Christmas tree—are rare. The bad ones—like an inoperative self-serve fuel pump, a flat nosewheel strut, or worse-than-forecast weather at your destination—are more common.
Some of the really bad surprises involve aircraft maintenance. Since my company manages the maintenance of about 1,000 GA airplanes, I thought I’d seen just about every sort of maintenance misfortune that can befall an aircraft owner, but the one I’m about to relate has to take some sort of prize.
It involves the owner of a Cirrus SR22—I’ll call him Mark—who was starting to get a bit concerned about the increasing oil consumption of his Continental IO-550-N engine. He was starting to notice increased oil on the belly behind the righthand tailpipe, and a buildup of sooty deposits inside that tailpipe. A maintenance-involved owner and a pretty sharp cookie, Mark’s suspicion was that the oil consumption was probably the result of lead-contaminated oil control rings in the right-bank cylinders (#1, #3, and #5). The presence of oily deposits on the #3 and #5 spark plugs seemed to confirm that theory.
Mark flew his airplane to a well-known Cirrus Service Center for further evaluation. The shop’s Director of Maintenance (DOM)—I’ll call him Steve—told Mark that he’d do a thorough borescope examination of the cylinders once the engine had cooled, and report back on what he found.
The next day, Mark received an ominous voicemail from Steve that started off with the words “Bad news…” and went on to say that the engine had “metal contamination” and “spalled cam lobes and lifters.” Mark also received a couple of low-resolution photos from Steve showing the SR22’s engine with the #3 and #5 cylinders removed, together with a statement that “the engine needs to be torn down.”
Needless to say, Mark was shocked. He had not given the shop permission to remove any cylinders. He’d only authorized a borescope inspection. Furthermore, the metal contamination diagnosis made no sense to Mark, because shortly before he took his plane to the shop, he’d performed an oil change and cut open the oil filter and found it clean as a whistle. Something wasn’t adding up. Mark bit his tongue and replied to Steve’s email by asking where the shop proposed to send the engine for teardown, and indicating that Mark was going to investigate alternative engine shops.
At this point, Mark contacted me for advice, and emailed me the low-resolution photos he’d received from Steve. I looked at the photos and told Steve that I didn’t see anything obvious wrong with his cam lobes, but that the quality of the photos was just too poor for me to offer an opinion as to the condition of his cam. I referred Mark to Continental’s Service Information Directive SID05-1B that provided very specific inspection criteria for assessing the airworthiness of cams and lifters on Continental engines. In pertinent part, SID05-1B says:
“If the visual cam lobe inspection reveals the presence of indentations or crack-like features in the surface along the cam lobe apex, use a sharp pick or awl and lightly move its tip over the suspect surface area. If the suspect feature has any depth, the pick tip will repeatedly catch in the groove or pits. If the indentation or crack is determined to have depth, the cam must be examined by a [Continental Motors] service representative to determine any additional steps required. If the cam lobe inspection only reveals normal signatures and there is no positive indication of any distress depth, …no further action is required.”
After studying SID05-1B carefully, Mark drove to the Service Center armed with a camera, an inspection light and a sharp dental pick, determined to carry out his own SID05-1B cam inspection and satisfy himself whether the condition of his cam truly warranted an engine teardown. Upon arriving at the shop, he made a beeline for the maintenance hangar.
You did WHAT???
Mark was totally unprepared for what he saw when he entered the hangar: His SR22 had no engine or propeller! As he approached the airplane, he discovered his engine sitting on a wooden pallet on the floor of the hangar. Apparently, the shop’s mechanics had removed it from the airplane without obtaining his authorization, asking for his permission, or even notifying him of what they intended to do. Mark was floored.
Cylinders #3 and #5 had been loosely reattached to the palleted engine in preparation for shipping it to the engine shop. Mark had one of the shop’s mechanics remove those cylinders so Mark could perform the cam inspection that he’d come there to do. He dutifully ran the sharp dental pick over the surfaces of all the exposed cam lobes (per SID05-1B) and could not find a single crack, pit, or other feature deep enough to catch the tip of the pick. Mark took a bunch of high-resolution photos of the cam lobes and sent them to me. They revealed only normal swirl wear patterns, with no evidence of significant distress.
Mark next asked for a sit-down meeting with both Steve and his boss (the shop’s owner). He gave them each a copy of Continental SID05-1B, walked them though the pertinent language, described how he’d probed the lobes with his sharp dental pick, showed them his high-resolution photos, and argued that Steve had simply been wrong in his assertion that the cam was spalled. He also pointed out that the shop had removed two cylinders without his authorization, and then removed the entire engine without his authorization. Mark insisted that the shop reinstall the cylinders on the engine and reinstall the engine in the airplane at the shop’s sole expense.
The shop owner was not amused. However, after considering the compelling evidence of Steve’s malpractice that Mark had presented, plus the complete lack of documentation showing that Mark had approved any of the disassembly that the shop had done, the owner appropriately concluded that he had little choice but to do the right thing. (I’d have loved to be a fly on the wall in that office after Mark left and the shop’s owner had his tête-à-tête with Steve.)
About a week later, Mark flew his airplane home from the shop, vowing never to return. On the flight home, he discovered the engine’s idle stop badly misadjusted and the propeller installed 180 degrees from the proper position. Rather than risk taking the airplane back to the Service Center, Mark decided to pay a local A&P to correct those two items.
Over the coming weeks, Mark discovered that his problem with excessive oil consumption had vanished. The shop installed new rings on the #3 and #5 pistons before reinstalling the cylinders, and apparently that cured the problem that had prompted this painful misadventure in the first place.
At least that was a pleasant surprise.