N546RV
Well Known Member
Took the club Citabria out to Lockhart for some BBQ today. Nice day to fly, only downside is that Citabria is pretty hilariously slow for a cross-country. Anyway, the plane was fueled to about 3/4 when I left Pearland, and at Lockhart I had about half tanks remaining. Probably enough to make it back to Pearland, but I was solo and not weight-limited, so I saw little reason not to top off. So I did.
Notably, this was the first time I'd ever fueled a high-wing airplane (I really appreciate PA-28s now). After finishing and stowing the pump, I made a quick visual inspection of both fuel caps before starting up, taking off, and heading for home.
I was about 20 minutes into the flight and level at 3500' when I glanced at the fuel gauges and got an unpleasant surprise. The right gauge still read full as expected (I'd checked both gauges prior to takeoff), but the left one was showing about 3/4 of a tank. I started at it for about 30 seconds before realizing that if there was ever a time for a precautionary landing, this was it. So I located the nearest airport (~15nm away) and got headed in its direction, while digging up the frequencies and other airport data I needed to go land there.
I have never been more acutely aware of the slowness of a Citabria than during those 15 miles to the airport. Every time I'd look at the left gauge, it would appear visibly lower than before. Clearly either the gauge was failing, or I was dumping fuel overboard somehow. Given that this happened after refueling, the latter was obviously the leading conclusion. I was certain I'd replaced both caps, but was I remembering wrong? Had I lost one?
By the time I was getting close to the airport, the left tank was reading under 1/4 tank. I consider that reading to be basically synonymous with "empty," so now I was getting pretty nervous about my fuel state. Fortunately, there was no other traffic, and I was able to easily expedite my pattern entry. Except I got carried away here, and kept my pattern a little bit too tight. I turned final way too high and close, and even putting the Citabria in a big old slip, it was pretty clear that I wasn't going to touch down until well past the halfway point of the (5000') runway.
This led to another fun decision point: Do I push on into the landing with a significantly decreased safety margin, and risk ground looping or going off the runway? Or do I go around and risk fuel exhaustion? The left tank was still reading about 1/4. I decided that going around was the better choice by a long shot - even if the engine quit on downwind, it shouldn't have been difficult to make the runway.
The second approach was much better. After taxiing to the ramp, catching my breath, and shutting down, I hopped out. The problem was immediately obvious, as the top of the right wing had lots of nice blue streaks. And now I could see that the right fuel cap was slightly crooked. I wouldn't have thought you could "cross-thread" a cap like that, but by Jove I did it. A quick physical check showed that the cap could be installed correctly. Ah, operator error, the most disappointing thing to have to acknowledge.
It took 14 gallons to top the plane off again. With 35 gallons usable, and the right tank basically full, I figure I probably had 4-5 gallons at best in the left tank. Based on some rough guesses at the duration of the flight, I figure I was pumping a gallon overboard every 2-3 minutes. So I made my landing with probably about ten minutes of usable fuel remaining.
So, what did I do wrong? Obviously, I failed to properly check the security of the caps. Specifically, I failed to visually recognize the improperly installed right cap on the ground. A closer physical inspection might have revealed the problem, but mostly I think this was an issue of ignorance and lack of attention to detail on my part.
Another bad judgment call was this: after getting established on course to my precautionary landing site, I went ahead and started a descent. I was thinking in terms of doing my usual gradual descent, but in retrospect staying "high" would have given me more options had I actually exhausted the fuel.
I also didn't check behind me when identifying an airport to divert too. I had my iPad with Foreflight, and I simply picked an airport about 45? off my nose to go to. Main criteria was that it had a not-short runway and fuel available. At that time, I didn't realize just how fast I was losing fuel, or else I might have concerned myself a bit more with finding the absolute best/closest diversion point.
Overall, I believe I handled the situation well. I made a fairly prompt decision to land, committed to a site, and immediately focused on briefing myself for the unexpected landing. But some of my execution could have been better.
This was a situation I'd never thought through before. I was unprepared for the rapidity with which fuel was leaving the airplane, and I was unprepared to handle it. The immediate temptation was to firewall the throttle and make best speed to my destination, but if I was missing a fuel cap, going faster might well cause the fuel to go overboard faster. The prospect of going slower just promise to make an already excruciatingly long trip even longer.
I still don't know the best answer to that question, and I'd welcome anyone's thoughts on handling this situation.
Fly safe. Know your airplane, so you know when something's not quite right. Maybe most importantly, keep your periodic scan going. If I'd gone another ten minutes without noticing the left tank getting low, we might be having a very different discussion right now.
Notably, this was the first time I'd ever fueled a high-wing airplane (I really appreciate PA-28s now). After finishing and stowing the pump, I made a quick visual inspection of both fuel caps before starting up, taking off, and heading for home.
I was about 20 minutes into the flight and level at 3500' when I glanced at the fuel gauges and got an unpleasant surprise. The right gauge still read full as expected (I'd checked both gauges prior to takeoff), but the left one was showing about 3/4 of a tank. I started at it for about 30 seconds before realizing that if there was ever a time for a precautionary landing, this was it. So I located the nearest airport (~15nm away) and got headed in its direction, while digging up the frequencies and other airport data I needed to go land there.
I have never been more acutely aware of the slowness of a Citabria than during those 15 miles to the airport. Every time I'd look at the left gauge, it would appear visibly lower than before. Clearly either the gauge was failing, or I was dumping fuel overboard somehow. Given that this happened after refueling, the latter was obviously the leading conclusion. I was certain I'd replaced both caps, but was I remembering wrong? Had I lost one?
By the time I was getting close to the airport, the left tank was reading under 1/4 tank. I consider that reading to be basically synonymous with "empty," so now I was getting pretty nervous about my fuel state. Fortunately, there was no other traffic, and I was able to easily expedite my pattern entry. Except I got carried away here, and kept my pattern a little bit too tight. I turned final way too high and close, and even putting the Citabria in a big old slip, it was pretty clear that I wasn't going to touch down until well past the halfway point of the (5000') runway.
This led to another fun decision point: Do I push on into the landing with a significantly decreased safety margin, and risk ground looping or going off the runway? Or do I go around and risk fuel exhaustion? The left tank was still reading about 1/4. I decided that going around was the better choice by a long shot - even if the engine quit on downwind, it shouldn't have been difficult to make the runway.
The second approach was much better. After taxiing to the ramp, catching my breath, and shutting down, I hopped out. The problem was immediately obvious, as the top of the right wing had lots of nice blue streaks. And now I could see that the right fuel cap was slightly crooked. I wouldn't have thought you could "cross-thread" a cap like that, but by Jove I did it. A quick physical check showed that the cap could be installed correctly. Ah, operator error, the most disappointing thing to have to acknowledge.
It took 14 gallons to top the plane off again. With 35 gallons usable, and the right tank basically full, I figure I probably had 4-5 gallons at best in the left tank. Based on some rough guesses at the duration of the flight, I figure I was pumping a gallon overboard every 2-3 minutes. So I made my landing with probably about ten minutes of usable fuel remaining.
So, what did I do wrong? Obviously, I failed to properly check the security of the caps. Specifically, I failed to visually recognize the improperly installed right cap on the ground. A closer physical inspection might have revealed the problem, but mostly I think this was an issue of ignorance and lack of attention to detail on my part.
Another bad judgment call was this: after getting established on course to my precautionary landing site, I went ahead and started a descent. I was thinking in terms of doing my usual gradual descent, but in retrospect staying "high" would have given me more options had I actually exhausted the fuel.
I also didn't check behind me when identifying an airport to divert too. I had my iPad with Foreflight, and I simply picked an airport about 45? off my nose to go to. Main criteria was that it had a not-short runway and fuel available. At that time, I didn't realize just how fast I was losing fuel, or else I might have concerned myself a bit more with finding the absolute best/closest diversion point.
Overall, I believe I handled the situation well. I made a fairly prompt decision to land, committed to a site, and immediately focused on briefing myself for the unexpected landing. But some of my execution could have been better.
This was a situation I'd never thought through before. I was unprepared for the rapidity with which fuel was leaving the airplane, and I was unprepared to handle it. The immediate temptation was to firewall the throttle and make best speed to my destination, but if I was missing a fuel cap, going faster might well cause the fuel to go overboard faster. The prospect of going slower just promise to make an already excruciatingly long trip even longer.
I still don't know the best answer to that question, and I'd welcome anyone's thoughts on handling this situation.
Fly safe. Know your airplane, so you know when something's not quite right. Maybe most importantly, keep your periodic scan going. If I'd gone another ten minutes without noticing the left tank getting low, we might be having a very different discussion right now.
