 |
| Author | Post |
|---|
rkaplan
Administrator
|
Posted: Fri Sep 22nd, 2006 08:11 pm |
|
Yesterday afternoon the weather was gorgeous. I departed KCMH for KWAY on an IFR flight plan. All was fine for 20 minutes. I was in cruise at 5000 feet being vectored a good bit out of my way and then I heard a "pop" and my main alternator went off line and my standby B&C alternator came on. Within 5-10 seconds all the avionics dimmed and smoke came out of the panel. I immediately hit the master switch and the smoke went away. The plane flew fine except the mixture control was frozen in place -- so in my mind the status of the fuel system was unknown, i.e. did the cable freeze and leave fuel leaned for cruise or did something break off and leave fuel pouring out somewhere?
So I hit nearest on my Garmin 296 and the choices were 4I9 5 miles away (3400 foot runway) or MNN 13 miles away (5000 foot runway). I realized I needed a no-flap landing, which is doable at that length if the approach and speed are managed well, but I would not want to consider a go-around because (a) I didn't know if there would be enough fuel flow to the engine for a go-around; and (b) if fuel were leaking somewhere then full throttle might make it worse. I debated which airport to land at and decided I wanted to get down quickly since I could not determine for sure that the problem was contained. So I chose the nearest airport with the shorter runway. I pumped down the gear manually.
I landed without incident except I could only shut down the engine with the fuel selector set to off (i.e. the mixture was still frozen). There was no further smoke upon landing. No circuit breakers had popped. The ammeter needle had apparently been violently pegged (direction unknown) since the needle literally broke off and was sitting loose inside the gauge.
The airport manager drove up and said Columbus Approach asked if I landed and wanted him to relay to me that they assumed I had an electrical problem and figured I was landing at 4I9 based on my airplane as a primary target and that they had cancelled my IFR since they knew I had landed. The airport manager (Butch Fisher) turns out to be an aviation jack of all trades. He lives in a really nice house on the airport and is an A&P/IA, airplane/helicopter/aerobatic instructor, and the airport maintenance department all in one. He seems quite knowledgable and capable.
After I rented a car, I was curious if my avionics were fried so I turned the battery master back on. The smell of smoke returned and it took a couple tries for the master to turn off. I took the cowling off to see the source of the smoke and it was from the right-side firewall by the mixture cable. The mixture cable is severed in two. It is lying near an intake manifold pipe.
It would seem that something caused an electrical arc which melted the mixture cable but we don't know the primary cause yet. Was the electrical problem first or the mixture problem first? Perhaps the mixture cable snapped and shorted out some electrical component?
Obviously we are looking into the root cause in detail. Anyone else have this occur before?
Any other thoughts on how the situation could have been handled? One friend suggested a quick Mayday before turning off the master though at the time I just wanted everything off before the situation got worse. I briefly thought of landing off-airport in the event I had fuel pouring into the engine compartment though it appeared all resolved when I turned off the master. The landing turned out fine but I suppose I put myself into a must-land situation with a go-around improbable or at least undesirable but then again I didn't want to have to fly further than needed and I have surely done many no-flap landings with students.
I drove home and got back 11:30PM. Long day for sure but it could have been a lot worse.
____________________
Richard Kaplan, CFII
rkaplan@flyimc.com
http://www.flyimc.com
|
rkaplan
Administrator
|
Posted: Tue Sep 26th, 2006 01:26 am |
|
After further inspection, the problem appears to have been due to the mixture cable coming into contact with the battery cable distal to the master solendoid. The resulting electrical arc not only severed the mixture cable but also damaged the throttle cable.
Interestingly (at least on the ground), if the throttle cable had become inoperative, that would have left the engine operating with no ability to control it with either the throttle or mixture cables. I do not think a landing would be viable with only the prop control, thus apparently leaving the best option for landing to be a deadstick landing with the engine stopped at a time/location/place of the pilot's choice by turning the fuel selector to off. Thus the solution to this situation might have required something most simulator students and instructors tend to feel is unrealistic -- a simultaneous deadstick landing with total eletrical failure... fortunately it did not come to that.
____________________
Richard Kaplan, CFII
rkaplan@flyimc.com
http://www.flyimc.com
|
Current time is 04:13 am | |
|
|
|
|
