The NTSB added: “…Without the cap in place, fuel escaped from the left main fuel tank and subsequently starved the engine of fuel during the climb,"
WHAT climb? They never even reached 300’.
Tell me HOW a missing fuel cap on the top of a tank will starved the engine of fuel right after takeoff.
20 gallon capacity, 17 usable in level flight. There is an AD that requires placarding the fuel gauges with a yellow line. That yellow line starts at the 10 gallon mark prohibiting takeoff when the fuel level gets down to the yellow as you can have fuel starvation problems. Not difficult to burn 1-2 gallons during run up and taxi, especially when you have the electric prop as checking it takes longer and is totally different than a hydraulic. That leaves approximately only 5 gallons to siphon off causing a potential fuel starvation event depending on take-off / climb attitude and the nuances of that particular air-frame’s fuel bladder installation. A missing cap would siphon off five gallons very quickly. Not saying every Bonanza quits when the fuel reaches the yellow, but take off is prohibited when in that range.
Yup Stuff like this happens. Was an instrument instructor 40 years ago and had a flight instructor who wanted his IFR rating. Took a PA-23-250 which he rented and he left the left fuel cap loose on a very cold morning at YYZ.
Whooosh goes the fuel. Barely made it to YHM but he learned his lesson!
Reminded him to tell himself and his students to complete the preflight without interuption!
I dunno, the siphon explanation doesn’t do it for me either. The yellow-line restriction is related to turning-induced un-porting of the aft-located fuel pickoff point, causing air ingestion. That would have occurred basically at the start of the takeoff roll and before any siphoning could occur. Assuming he started with enough fuel to preclude the initial un-porting (did he?) I can’t visualize siphoning radical enough to empty the tank to the point of pulling all fuel completely away from the pickoff point.
But, like the explanation that he was interrupted and that resulted in the fuel cap falling off, we’re just speculating.
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First off a few reminders on the definition of the word “probable”:
Probable:
Hey Doug P., you should look up the definition of pedantic.
I agree that the idea of an entire 20 gal tank being drained in a matter of seconds or even a few minutes is highly unlikely. Fuel would have to be gushing out like a firehose! I’m ashamed to admit I’ve made this mistake (twice!), and I lost significant fuel, but not the entire tank - maybe a third - and that was over a long flight. However, if the tank’s only vent was in the cap, then the low pressure over the wing could stop the fuel from flowing even if the tank was full. Most Cessnas have dual vents, one in the cap and a ram-air vent. Not sure about the older Bos. Maybe someone with specific knowledge could comment.
I agree with Mark. I had the experience of leaving a fuel cap off one time, in the only tank with fuel in it. This was in a Cessna 180, and the tank with fuel only had about 18 gallons in it for a 20 minute flight. I did not realize that the cap was off, hanging by the chain, until preparing to re-fuel at my destination! Nice stain on the wing too. Remember the articles called “I Learned About Flying From That”?
I think that the fuel siphoning eventually reduces or stops when the fuel level is quite low, but that takes time. In a Bonanza, if fuel pressure is affected, there is always the electric fuel pump.
Ian Hollingsworth
DER Flight Test Pilot
Love it! Been accused of being “punctilious” and sometimes I wear it like a medal. For all we know there’s probably a mathematical way to compute the volume of avgas that would be sucked out of the top os a Bonanza wing with the fuselage cap off. Regardless, I trust the exhaustive analysis done by the NTSB to come up a probable cause more than some armchair astrophysicist’s. Just sayin.
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Possibility of water in the fuel or tanks wasn’t mentioned. If the left tank was empty then the fire would be from only the fuel in the right tank. Was their any forensic evidence that this right tank fuel was or was not solely responsible for the fire?
"According to the NTSB, “a relatively flat, open, grass-covered area extended for about 2323 ft in the takeoff direction from the accident site to the airport perimeter.” Assuming the pilot departed the +5000ft RWY 1, he he would see about 1200ft of grass ahead and houses to the left. I can’t find the 2323 ft grass field the pilot is apparently accused of rejecting. That said, if a mile is required to get a Bo to “treetop” altitude something likely more sinister than a loose cap is in play IMHO.
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Best WAG is that there was plenty of fuel in the left tank that was just filled and the cap not fully secured. Gobs of fuel. A huge post impact fire confirms there was still plenty of fuel on board the aircraft.
The real question becomes what was in the right tank (that still had a cap on it and was found selected at the time of the crash). Lack of fuel in the perfectly capped right tank is my “WAG”, not the left tank.
The examination that a cap was off the left tank means one of 2 things:
Tell me which sounds “probable” based on the information?
This has been the second consecutive story on fuel; both “conclusions” seem to not add up based on my limited 40 years of flying. The simple explanation here was that the pilot had the right tank selected on landing and subsequently forgot to switch to the left for takeoff. When the right tank suck air on takeoff, the pilot “knew” he had fuel so his first reaction was to turn back, NOT to look down and fiddle with the fuel controls. He crashed with the fuel selector still on the right tank and the good chance of a post crash fire from an open fuel tank with still at least 27 gallons.
The missing cap only played a part in the post crash fire.
That, and it was getting really dark at that time of evening. The view ahead into the darkness was probably not very good. Unfortunately it sounds like the engine did not regain any power or surges so the turn back did not happen. It’s real tempting to turn back to the “known good” than head forward into the “dark unknown”.
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The report states that “daylight visual conditions prevailed”. The sunset time for the departure airport on September 24,2017 would have been between 7:15-30 pm approximately. The NTSB make some suppositions with regards to the pilots selection of the fuel tank selection and fuel cap affecting fuel starvation as they were unable to make a definitive conclusion as to why the engine quit or lost power. The focus of the article strayed from distractions and interruptions during a pre-flight and secondly the cause of the resulting crash (stall) to why the engine quit, which was not determined conclusively. Here’s a link to the actual full report.
https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20170925X25031&AKey=1&RType=Final&IType=FA
Nevertheless interesting discussion.
Probable in this context means that’s the most likely explanation we’ve been able to think of. I was involved in an accident that the NTSB’s best guess didn’t fit the timeline. They were relying on some erroneous “witness” testimony.
Mark’s explanation sounds good to me.
I’m not familiar with the Bonanza in question (Air Force and airline heavies, mostly), but I 'd like to contribute the following: guessing that the fuel filler is visible from the cockpit, is there a chance that the pilot got a glimpse of the departing fuel cap, or was doing a quick glance-around just after lift-off, and kick-started the response sequence which led to the resulting crash?
I can’t speak to the rest of the accident sequence, but an open gas tank on a Bonanza will drain in a real hurry. A year or two ago I watched one of our pilots have a gas cap pop off his A-36 at takeoff. There was quite the plume of gas coming off the wing. I don’t remember how long it lasted, but by the time he made it around the pattern and landed the tank was empty. Fortunately the cap was on a safety chain, so all he lost was the gas. (Also, fortunately, he was flying on the other tank, or got to the other tank in time.) His remark afterwards was “Well, that’s the most expensive pattern I’ve ever flown.”
I just recently left the oil filler cap off after adding a quart of oil to the engine on my C172. I took off and flew for an hour with the oil cap off. I had a nice mess to clean up off the side of the aircraft after landing. The probable cause was interrupting my normal flow of pre-flight and going back to add oil to the engine after completing my pre-flight. I learned a thankfully harmless, but messy, lesson to review the preflight again after any interruptions or deviation from the normal flow of the checklist.