Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.3 4.3bsd-beta 6/6/85; site ihnp3.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!ihnp4!ihnp3!dhp From: dhp@ihnp3.UUCP (Douglas H. Price) Newsgroups: net.aviation Subject: Re: T.O. in Cessna 172 Message-ID: <182@ihnp3.UUCP> Date: Fri, 8-Nov-85 15:15:27 EST Article-I.D.: ihnp3.182 Posted: Fri Nov 8 15:15:27 1985 Date-Received: Sun, 10-Nov-85 07:45:52 EST References: <769@bgsuvax.UUCP> <32838@lanl.ARPA> Reply-To: dhp@ihnp3.UUCP (45262-Douglas H. Price) Distribution: net Organization: ATT Bell Labs Lines: 131 Keywords: Cessna 152 engine failure Summary: Engine failure can show as low rpm Now that it has been about a year since this incident (and I am now somewhat removed from it) I would like to relate what happened to me in a C-152 while still a <40 hrs. student. It was about a month and a half before my wedding, and I was trying to finish up my required flying time so that I could get my license out of the way beforehand. In fact, my instructor, Jeff Williams, often seen here in net.aviation, suggested, "You've got to get your priorities straight, boy! What's more important, flying or getting married?" :-) Anyway, I rented 6246P, a 1980 vintage C-152 with long range tanks for an hour's worth of practice area work. This airplane is equipped with a Lycoming O-235-L2C model four cylinder horizontally opposed air-cooled engine. I was the first one out that day with the airplane. Checkout was normal. It was a somewhat warmer day than the last time I had flown, so I was prepared for sluggish response from the craft, though not nearly as bad as we shall see. I was alone (of course) but had full long-range tanks, so the weight was relatively near gross. The following is what I remember was said between myself and the tower one year ago. Forgive any technical inaccuracies from the tower's point of view. I normally see it from the pilot's point of view. 6246P: Aurora ground, Cessna six two four six Popa at Luminaire with information Alpha, and I'd like to be westbound today. Aurora Gnd: Cessna four six Popa, Aurora ground, taxi to one eight. 6246P: Four six Popa. As I taxied to the active runway I could hear a rattle I hadn't heard before. But, then again, every time I got into one of those airplanes they sounded a little different. The power runup test was completely normal. 46P's engine had a tendency to silt up with carbon deposits which needed to be burned off by leaning the engine during the static tests. Nothing unusual was noted. 6246P: Aurora tower, Cessna six two four six Popa ready at one eight. Aurora: Cessna four six Popa, Aurora tower, right turn approved, clear for takeoff. I then turned onto the runway and applied full power. Acceleration was sluggish. I noticed this problem relatively soon in the roll down the runway, but didn't do the correct thing and abort the takeoff. Finally after using about 3/4 of the 4500 foot runway, I managed to get the thing into the air. Now, not only was acceleration bad, but the rate of climb was anemic at best. Groundspeed stayed low, the attitute to hold the airspeed was low as well, and the rate of climb indicator reported a 150ft/min climb. The expected value at that temperature and a 75kt airspeed would have been around 500ft/min. As it was I was doing well to maintain that rate of climb at the best-rate-of-climb airspeed 68 kts. Once I had assured I would clear the power lines on the other side of the road, I finally got around to checking the tachometer. It reported that I was at 2000 rpm, 300 rpm low!! So it wasn't my imagination! It was real trouble!! 6246P: Aurora tower, four six Popa, I've got a problem here. Aurora: Four six Popa, do you wish to declare an emergency, sir? 6246P: Uh, negative. I'm not developing full power, and I'd just like to get this thing back on the ground. Aurora: Roger four six Popa, can either continue in the pattern to the right, third in order for landing, or I can give you a left turn for landing on runway two seven. 6246P: Aurora, four six Popa, I'll go right. Aurora: Roger four six Popa. Another mistake. If there really was a problem with the engine, it might quit at any second. I might be better to take an immediate vector to a runway. On the other hand, diverging wildly from what I had planned in the first place, a right turn (which would allow me to continue around the pattern) could be just as dangerous for a low-hours student such as myself. As I waited until I had reached a safe altitude to begin a turn, I listened to the engine a while longer. 6246P: Aurora tower, four six Popa, I've changed my mind, I'll take the left turn. Aurora: Cessna four six Popa, left turn approved, clear to land on runway two seven. Cessna four one Popa, go around.... Now came the, ahem, fun part. Rule 1: when in trouble stay in tight to the airport; you may have to glide it home. Rule 2: in the case of suspected engine trouble, especially that close in, don't touch the throttle until you are fully committed to the runway. Jeff had told me that most engine failures on landing occur when power is reduced for the landing. My turn to the left (gently, gently!) put me on a slightly far-out downwind for 27. Still with the throttle all the way in, I turned base for a short final. The flaps started coming out at this point. Finally, when I had more than enough energy to make the runway, I cut power back to a normal 1500rpm value. The engine didn't quit. Full flaps and a normal-feeling crosswind landing. Aurora: Cessna four six Popa, clear to taxi, remain on this frequency until fully stopped. 6246P: four six Popa. I taxied back to the FBO. The engine sounded normal again!! 6246P: Aurora tower, four six Popa, back at Luminaire. Aurora: Roger four six Popa. I climbed (shakily) out of left seat, went to the owner of the FBO and said, "You might want to take a look at the engine..." I sat in my car for a while and thought about my actions. Two days later I dropped by to see what they had found. The AP had the right side of the engine apart. A crescent shaped chunk of the piston skirt 1/3 of the way around one of the piston was missing. The AP said that the piece had fallen back into the crankcase and had gone bouncing around in there. That particular cylinder was developing no compression at all. The one on the opposite side was pretty bad off as well, and the other two had been on their way downhill. He gave me a fuzzy polaroid photo of the bad piston, an extra from the report supposedly going to the NTSB. The usual "storal of the mory" is of course, anything out of the norm is worth worrying about! -- Douglas H. Price Analysts International Corp. @ AT&T Bell Laboratories ..!ihnp4!ihnp3!dhp