airguy
Cleared for Takeoff
Capping off several hours of flying today, two legs from home in my 172, I was stopping in for a splash-and-dash fuel stop at a local ag strip. I dropped in fast, pump is at the end of the strip, 10 gallons as fast as we can pump it, crank it up, fast mag check, and lets go. Temps were high 80's, 2700 MSL field, injected 360 FP, 800 TTSN, 100LL, dual mags.
I've done this more times than I can count. All kinds of weather, all kinds of loads, every situation I can think of at this particular strip - been there and done it. This time everything looked the same, smelled the same, sounded the same, felt the same. I've got 7-10 knots south wind with 3000 feet paved into the wind and 2000 smooth dirt over-run, this is my back yard (figuratively speaking) and I'm all happy-happy.
Today was different. Just as the mains broke ground in my lightly loaded 172 (1 passenger, 25 gallons fuel, no baggage) I thought I heard something funny. Within a few seconds my dad in the passenger seat said "Uh oh, did you hear that?" and by that time the engine was quite noticeably missing. Not sagging rpm, but definitely missing and shaking. Full rich, boost pump, no change. I've still got the overrun ahead to put it down but its questionable if I'll get it stopped. I'm still holding better than 2400 rpm (not surprising at Vy in this airplane) and make the decision to continue, and drift right downwind off the runway while holding Vy for all the energy I can buy. Downrange is light pasture, rough but survivable. I make 400 feet, then 500, engine still missing and shaking but still making power, engine monitor offers no clue about whats happening, looks normal. I'm about 300-400 yards downwind (left crosswind) of the overrun at 500-600 AGL (it's kinda hard to tell when you heart is beating that fast) and start turning back left now, cranked over about 45 degrees with the engine still going but missing. As I get around the 90-degree point I see I have the overrun area made and pulled the engine to idle and said "Engine is dead, we're committed." With 20 degrees flaps dropped in at about 150 feet I just made the asphalt at the end of the overrun on a downwind landing. Rest of the landing sequence was cake.
Freaking engine stubbornly continued to run, and from that point absolutely refused to miss or show any sign of weakness at all. Turned off at the far end of the strip, turned into the wind, full power runup, leaned it, mag check, fuel pump on/off, changing tanks - you name it, I did it - nothing doing, engine was perfect now. I couldn't get so much as a hiccup.
I pulled the cowl, checked plugs, check wires, checked fuel lines, checked induction and air filter, check tank vents, no joy. Never found anything. Chalked it up to vapor lock due to the very short turn-around. Recowled and performed normal (for this aircraft) hot-start and full power runup until CHT's approached normal cruise, departed and flew normally for the last 2 legs.
It's not my first "Oh Crap" emergency landing, but it was my first with a passenger (and family, no less), so this one carried a bit more impact. It was also my first "impossible turn" though I've thought about it an awful lot. In the end it came down to a judgement call - I could put it down in the pasture ahead survivably (though certainly not happily) if the engine went balls-up right-friggin'-now or I could make the runway in 10 more seconds. I can't say what I would do in other circumstances, I just know what I did today - you have to play the cards you are dealt - and it worked. I will say this though - I was fully prepared to wrinkle metal to whatever degree necessary to walk away, I absolutely did not attempt the turnback just to save the airplane - it was a second-by-second analysis of energy management and assessment of plan A versus plan B.
I'm still bothered by the fact that I could not find a smoking gun culprit of the problem, but that's the nature of vapor lock. I'm sure others will critique my decisions, and I'm strangely comfortable with that because I'm here to give a crap about their critique. The decision-making process worked, the planA/planB/planC process worked, and we walked away.
I've done this more times than I can count. All kinds of weather, all kinds of loads, every situation I can think of at this particular strip - been there and done it. This time everything looked the same, smelled the same, sounded the same, felt the same. I've got 7-10 knots south wind with 3000 feet paved into the wind and 2000 smooth dirt over-run, this is my back yard (figuratively speaking) and I'm all happy-happy.
Today was different. Just as the mains broke ground in my lightly loaded 172 (1 passenger, 25 gallons fuel, no baggage) I thought I heard something funny. Within a few seconds my dad in the passenger seat said "Uh oh, did you hear that?" and by that time the engine was quite noticeably missing. Not sagging rpm, but definitely missing and shaking. Full rich, boost pump, no change. I've still got the overrun ahead to put it down but its questionable if I'll get it stopped. I'm still holding better than 2400 rpm (not surprising at Vy in this airplane) and make the decision to continue, and drift right downwind off the runway while holding Vy for all the energy I can buy. Downrange is light pasture, rough but survivable. I make 400 feet, then 500, engine still missing and shaking but still making power, engine monitor offers no clue about whats happening, looks normal. I'm about 300-400 yards downwind (left crosswind) of the overrun at 500-600 AGL (it's kinda hard to tell when you heart is beating that fast) and start turning back left now, cranked over about 45 degrees with the engine still going but missing. As I get around the 90-degree point I see I have the overrun area made and pulled the engine to idle and said "Engine is dead, we're committed." With 20 degrees flaps dropped in at about 150 feet I just made the asphalt at the end of the overrun on a downwind landing. Rest of the landing sequence was cake.
Freaking engine stubbornly continued to run, and from that point absolutely refused to miss or show any sign of weakness at all. Turned off at the far end of the strip, turned into the wind, full power runup, leaned it, mag check, fuel pump on/off, changing tanks - you name it, I did it - nothing doing, engine was perfect now. I couldn't get so much as a hiccup.
I pulled the cowl, checked plugs, check wires, checked fuel lines, checked induction and air filter, check tank vents, no joy. Never found anything. Chalked it up to vapor lock due to the very short turn-around. Recowled and performed normal (for this aircraft) hot-start and full power runup until CHT's approached normal cruise, departed and flew normally for the last 2 legs.
It's not my first "Oh Crap" emergency landing, but it was my first with a passenger (and family, no less), so this one carried a bit more impact. It was also my first "impossible turn" though I've thought about it an awful lot. In the end it came down to a judgement call - I could put it down in the pasture ahead survivably (though certainly not happily) if the engine went balls-up right-friggin'-now or I could make the runway in 10 more seconds. I can't say what I would do in other circumstances, I just know what I did today - you have to play the cards you are dealt - and it worked. I will say this though - I was fully prepared to wrinkle metal to whatever degree necessary to walk away, I absolutely did not attempt the turnback just to save the airplane - it was a second-by-second analysis of energy management and assessment of plan A versus plan B.
I'm still bothered by the fact that I could not find a smoking gun culprit of the problem, but that's the nature of vapor lock. I'm sure others will critique my decisions, and I'm strangely comfortable with that because I'm here to give a crap about their critique. The decision-making process worked, the planA/planB/planC process worked, and we walked away.
Just asking. 
