Deviation from normal operations results in engine losing power

This is an excerpt from a report made to the Aviation Safety Reporting System. The narrative is written by the pilot, rather than FAA or NTSB officials. To maintain anonymity, many details, such as aircraft model or airport, are often scrubbed from the reports.

I returned from a short flight in my Twin Bonanza 50 and ordered fuel at the FBO. The instructions were to top off both inboards and add 20 gallons/side on the outboards of 100LL. The outboards were both empty, so this should have given me 44 gal/side in the mains and 20 gal/side in the aux (770 pound fuel load, which is my standard).

I stayed with the plane to show the line person the filler locations and ensure that the fuel was 100LL. I then went into the FBO. I paid for the fuel but got no receipt, due to a change in their payment system being ongoing.

I then returned to the aircraft, started it, and put it in the hangar. The next morning I returned to preflight for a trip with my entire family (me plus four). My preflight checks oil first. This was done and OK. I then check fuel quantity using a calibrated dipstick. I then sump. I work left to right. The first dipstick goes into the left aux tank. It was completely full. I then measured the left main, which was also completely full. I concluded that the line guy had topped all four fillers and the aircraft would be overweight without removal of my spares kits, my tools, and some baggage.

As I was going to measure the right tanks, my youngest child said he had to go to the bathroom. He is undergoing chemotherapy and my wife and I respond to bathroom requests quickly.

I stopped the preflight and we took him to a bathroom nearby. I resumed the preflight upon my return, but was only two or three minutes into it when he had to go to the bathroom again.

When we returned from the second bathroom trip I finished measuring the tanks and wrote the quantities in my preflight form. I wrote “LM – 44, LA – 46, RM – 44, RA – 46.” I then sumped the fuel, which was OK. Ordinarily I would pour the sumped fuel into the right main filler but I put it instead into my power tug because I did not want one ounce of extra weight in the plane.

I then did a weight and balance to reduce the weight until we were at max gross. I had to remove material from the plane that is ordinarily kept there.

We then boarded and flew from ZZZ1 to ZZZ2 without incident. At ZZZ2 we dropped off our three kids with grandparents and prepared for the next leg to ZZZ3.

I always buy fuel when I stop anywhere and then dip and sump it. However, I had loads of fuel because of the over-fueling at ZZZ1 and ZZZ2 is only a 4,000 foot runway. I apologized for not buying fuel and promised to buy some when coming back through. I did not dip the tanks.

I fired up the plane and my wife and I took off for ZZZ3. While in cruise, about 25 minutes into the flight, the right engine abruptly lost power. I looked and saw that it had no fuel pressure. I engaged the right boost pump. Fuel pressure returned to normal and the engine ran normally. I concluded I had lost the right engine-driven pump.

About one minute later it started to surge again. I switched to the right aux tank but this did not help. I still believed I had lost the engine driven pump, but I had run through the checklist and was not able to restore power.

I decided not to mess with it further in the air. I went through the shutdown list and feathered the right engine. I then called Center to notify. Center suggested ZZZ and I concurred. I descended toward ZZZ, in and out of IMC. I loaded the RNAV approach as it looked like I might need it. I did a 360 at the holding point to lose altitude. I decided to make a left racetrack even though that was the unprotected side of the hold because I wanted to turn into the running engine (I was way above any obstructions). I intercepted the centerline and flew the approach on the left engine. The approach and landing were uneventful. I was able to taxi in and park on the left engine.

The FBO at ZZZ told me they had already contacted ATC and informed them I was safely down. We dropped our bags at the FBO and my wife started trying to get a rental car.

I went out to the plane and opened the cowlings to see if there was anything obvious. There wasn’t anything. All fuel lines (including return) were intact. I visually inspected the engine driven pump but nothing was apparent. I sat thinking through the symptoms and finally went and pulled the right main filler cap. It was bone dry. I ordered fuel.

After adding fuel the engine started and once the prop spun fast enough to get out of the feather detents it returned to normal operation.

There were only two possible explanations: (1) A massive fuel leak, but there was no evidence for that; or (2) The ZZZ1 line guy filled both aux tanks, and filled the left main tank, but put no fuel at all in the right main tank. I think #2 is what happened.

I thought I had dipped the right main (I even wrote it on the form) but the double interruption in preflight must have meant that I started again in the wrong place and never checked the right main. 

After the initial ground start I again stopped to check for fuel leaks. There were none. I then did a 30 minute ground run, all of which was normal. We reloaded the plane and took off for ZZZ3. The plane has had no trouble since. It was simply a dry tank.

But it was set up by the following unusual circumstances all lining up: (1) Line guy fails to fuel as directed (2) Problem not immediately caught because I was just putting it in the hangar and did not dip as per usual, (3) Lack of fuel receipt, which would have shown the wrong quantity, (4) Double distraction in preflight, (5) further distraction by consternation over being heavy and having to unload the plane, (6) Failure to take fuel at ZZZ2, and (7) Failure to dip at ZZZ2 anyway.

Lessons Learned: (1) If you are interrupted in preflight start over from the beginning; (2) Dip the fuel every time before you leave the ground. The landing at ZZZ2 was the first takeoff without dipping I can remember in many years. (3) With plenty of altitude under you maybe consider working the restart problem a bit longer but not much longer because it’s better to work that problem on the ground.

The reason for #3 is I should have been able to restart the right engine. If I had left the right selector on aux (which had about 40 gallons in it) for a minute or two I suspect the engine driven pump would have re-primed (There is no boost pump available for the aux tanks in the BE-50).

Even better: I should have cross fed the right engine from the left main and used the left main boost pump to re-prime the engine driven pump. This last option would have worked and power would have been restored.

On the other hand, I am glad I have done training at least once per quarter and the actual handling of the aircraft was not challenging, even though it was an IMC approach down to about 1,500 feet. I think this is the main reason I thought “Just cage the ***%@@ thing and figure it out on the ground.”

In writing this explanation I want to make plain that responsibility for all these events rests with me. Line guys make errors and it is the pilot’s job to catch them. It is striking to me that there were three separate events deviating from my normal habits of operation: Inspect fuel immediately after fueling, do not re-start a pre-flight in the middle, never take off without dipping all four fillers. Had I conformed to my normal habits on any of the three, this would not have happened.

Lastly, I feel a bit bad about declaring and tying up resources. However I would do it again. ATC was just as helpful as you would expect and it was nice to be able to offload distractions, looking up weather and frequencies, when I was single engine in IMC.

Primary Problem: Human Factors

ACN: 1819298