++safety Alert++

Jim Smith · #1 10-29-13, 08:22 PM

Hey guys. Flew today and burned 15 gallons. Both sides took an almost equal amount upon refueling. Not sure if exercising the valves corrected the problem or this condition only occurs after burning more than 50 gallons. The problem occurred after 50 gallons used (67 total). I rarely go that high without refueling. I'll continue flying and be watching the fuel gauges for uneven burn and topping off after each flight. I'll keep everyone advised.

Jim Smith · #2 10-31-13, 04:24 PM

After analyzing of the conditions and circumstances, discussions with several fine mechanics and Skymaster specialists including Owen Bell and Don Neiser, we've all come to the conclusion the only way this could've occurred is through one of the fuel valves. How, we're not exactly sure. Possible trash, weak spring(s), bad o-ring(s), or internal corrosion. My valves look beautiful on the outside but are original and have never been rebuilt so who knows what the insides look like. There is the possibility that one valve was slightly out of detent but it would've been only ever so slight. My future course of action and recommendation to other owners is, during your preflight make sure you hear each valve click as you put it into position, if it had been previously moved out of position from the mains. The cables from the valve selector handles to the valves do tend to get some slack and play. Adjust if necessary. Additionally, even though I'm not aware of any Cessna SID or an AD, it would be prudent to remove your valves and go through and rebuild them if they've never been rebuilt. At the very least inspect them internally. Being a 1969, mine are 44 years old and I'd have to imagine there may be some stuff going on in there that probably isn't good especially where there's any rubber concerned. You can maintain your aircraft in tip-top condition and one thing like this, that isn't required to be rebuilt unless it's broken, can take you down. There have been too many Skymaster crashes attributed to fuel exhaustion and who knows if this could be part of the reason why. Also, if you have a fuel flow/totalizer system, these add a great level of confidence with fuel usage, but continue monitoring for uneven burning from your good old fuel gauges. Thanks to everyone for your input.

hharney · #3 10-31-13, 05:16 PM

Jim

Thanks for the report. Have you looked into the parts to rebuild the valves? It seems I remember some Skymaster folks were looking for parts or the parts were out of price to justify. Let me know if you have rebuilt yours or have looked into the parts to do so.

Thanks

Jim Smith · #4 10-31-13, 05:44 PM

Herb, both Owen Bell and Commodore Aerospace (Don Neiser) said they can have them rebuilt through somebody they use for $2000 (owen) to $2500 (commodore) ea. That includes re-plating, new springs, balls, seals etc. if necessary. My mechanic rebuilt one on a different Skymaster I have. Inspected, cleaned, and put in new O-rings for just a couple bucks for the o-rings plus his labor. We rebuilt it because it was leaking. Don't really know if springs or balls were bad, but they looked good and at least got a chance to look inside.

Jim Smith · #5 05-03-15, 02:11 PM

Hey guys just realized I never posted a follow-up with the solution to this problem. Upon inspection with a mirror and flashlight we noticed the tiny ball that pops into the detent appeared to be missing. Removal of the valve confirmed this. We replaced the spring and ball and everything is fine. Amazing how one tiny ball bearing sized item can create such a major and potentially deadly issue. Not sure if the ball popped out on it's own or when the valve had been removed and serviced by a mechanic previously.