421 Catastrophic Engine Failure

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    I had a RAM engine with 1500 TBO that threw a rod on climeout 5 minutes after takeoff. After departure, power was set at climb power for both MP and RPM. Mixture was full rich at the time. The # 1 cylinder appears to have spun a bearing, created friction on the crank, was then “welded” to the crank, broke off and the piston and other half of the rod and piston went flying through the back of the case.

    I have Shadin fuel flow, JPI for the CHT and EGT, and there was no indication that anything was wrong.

    Is there anyone out there who may have a clue as to what the hell happened here?

    Is a 421 Catastrophic Engine Failure something that happens normally?

    I run my engines with at least 20 to 21 GPH per side depending upon the air temps, engine temps and the like. Never run it less in cruise than 20 gal a side. I always assumed a conservative attitude when it comes to these engines.

    Yet, here I am.


      Ron, I’m sorry this happened to you. Glad you handled it well.

      No, this is not “normal” but it does happen occasionally as it does with all piston engines (and some turbines as proven by the Qantas A380 episode recently). You were just one of the unlucky ones.

      Are you certain of the cause of failure? Did you send the engine to RAM and was this their assessment?


      This is always possible in any Piston Engine. I have dodged an engine failure with nearly 4000 hours of turbo piston time maybe I’m overdue. I actually love the GTSIO and like any engine if properly flown most likely you will have little or no problem. I personally use 380 CHT as my maximum it is a good reasonable temp. Not that it would have helped your problem. Your problem is probably most often seen in newly overhauled engines. The failure rate of piston engines is highest from 0-500 hours since major overhaul after that it goes down. There is not a lot of data on engines after TBO since most people overhaul them at or around that time. Don’t be afraid of these engines they normally don’t do this. You did you handle the situation very well, and the other one took you to a safe uneventful landing. We got our 421 set up to run LOP which gets our fuel burn down to 17-18 GPH and lose only 3 knots of speed. Feel free to call or email me if you want more info on that experience. RAM is very knowledgeable but they just won’t accept the proven science of LOP operations.

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