I have a story to convey that is very alarming for me and I'm still being haunted by what could have happened. I've been told by many aviation experts that "I can count my blessings" I didn't have an engine fire or engine shutdown while cruising at 15,000 feet last year over rugged terrain and low IFR enroute conditions over New Mexico.
On 17 October, 2018, I was repositioning my aircraft (2015 M20TN) from Atlanta (KPDK) to Las Vegas Henderson Executive Airport (KHND) with one fuel stop in Clinton, Oklahoma. The first leg went just fine. My fuel stop in Clinton consisted of grabbing a bite to eat at McDonalds (not many food choices in Clinton), then returning for the final leg home. I arrived back at the airport an hour later, sumped the tanks with the 75 gallons of fuel I had pumped earlier, and I was ready to file my new IFR flight plan via ForeFlight. I fueled my tanks especially full on this leg because of enroute low IFR weather 1/2 way to my destination, high terrain and lack of close alternate airports along the way.
After takeoff in good DAY VFR conditions, I smelled 100LL fuel, which was a bit surprising, but I discounted it, since I assumed it was caused by filling the tanks as high as I could (100 gallons). In the 2015 Mooney Acclaim Type S, normally I don't top the tanks due to the added weight for shorter flights. In my previous 1998 Mooney, I once smelled fuel in the cabin after takeoff six months after my tanks were resealed. The culprit was a few loose screws behind the pilot's sidewall that links to the fuel senders in the wing. In that instance, fuel was leaking from those screws very slowly and making a blue mess behind the interior sidewall. I ended up fixing the leak myself under direction of the "Weep No More" repair center. That fix entailed removing the pilot's seat, removing the left sidewall, and tightening the screws carefully and cleaning the blue stains, all which I could do as a pilot/owner legally.
During cruise, I made a note to contact my Mooney Service Center in North Las Vegas the following day to have the fuel smell addressed. Again, I assumed the fuel vapor was primarily caused by a small fuel seepage from a cabin screw behind the sidewall.
The fuel smell continued after two hours, so I knew it wasn't due to overfueling. It must have been the fuel seepage into the cabin.....so I thought. About an hour outside of Henderson Executive, while talking to Los Angeles Center, my G1000 fuel range ring all of a sudden showed I had five minutes of fuel remaining from 60 minutes I was suppose to land with. My fuel gages still showed I would have 20 gallons remaining on landing, which is my normal reserve on such a long cross-country flight. I discounted the G1000 fuel range ring as a malfunction, but a later review of my G1000 engine parameters database showed my fuel flow spiked from under 18 gph to 35 gph over a five minute period. I relied on my fuel gages, burn rate, and time. The G1000 fuel ring is not something I rely on, but is an advisory "nice to have visual display" only.
I was cleared for the visual approach into Henderson Executive, made a smooth landing and taxiied to my hangar with the fuel gages showing I had 20 gallons remaining. Since I had 32 hours on the oil and since the engine oil was still hot, I decided to do an oil change right then and there. After uncowling the engine and draining the hot oil, I noticed the firewall, nose gear doors (inside and outside), underbelly, and parts of the engine right next to the 1600'F+ dual turbo-chargers were coated with 100LL thick blue stains. I was in shock, because I'm super meticulous with my plane's maintenance, aircraft cleanliness, and I've never seen any leakage before like this with any aircraft I've owned in the past. This was a very SERIOUS leak. The only maintenance I've had done in the area was to "replace the main fuel pump" and to "reposition fuel line to prevent chafing". This was done two years ago. The MSC that accomplished this advised me they did not touch the fuel line in question.
The next morning, I came back out to the airport to finish the oil change and to start the engine to find out where the fuel leak was located. Under the direction of my Mooney Service Center both in Atlanta and North Las Vegas, I started the engine, let it run at 1000 RPM's and had another pilot take video of the engine during the ground run at 1000 RPM's. We had an extensive safety briefing before the runup due to the spinning propeller. We have video of the leak, and it was a massive leak near the top of the firewall, where the fuel transducer and main fuel line are located. The fuel was literally gushing out extensively and spraying all over the firewall. It was not a pretty site to see and as I said before, I'm told that it was a miracle there was no fire or engine failure while in cruise flight.
The area where the leak is located is wrapped up in orange fire-sleeve materials. About a week later, I had my MSC director of maintenance drive an hour to my hangar to diagnose the issue. His corrective action was, "TIGHTENED FUEL LINE ON FUEL TRANSDUCER". He found that this connection was not even finger tight. This area is on the upper rear firewall above the turbo chargers on the TSIO-550G engine. The fuel connection was about to let loose completely. I was flying 4 hours in that condition with considerable fuel spraying out. He said that this fitting is tightened from the factory and should never come loose on its own. He also said that it's something NEVER checked on annual or 100-hour inspections, because it's not suppose to come loose. I verified this with other leading Mooney Service Centers across the country and they advised me the same thing.....this main fuel fitting is NEVER checked on annuals. It's wrapped up in thick fire sleeving and there's never a need to check it. My MSC mechanic was super surprised that the plane didn't have a complete engine failure or especially a fire with the glowing red hot turbo chargers just below. Note: This main fuel line fitting cannot be safety wired, so it relies on proper tightness.
That following week, I drove to the Las Vegas FSDO office in Las Vegas and provided all of my photos to document the issue. They were VERY interested and directed me to submit all of my documentation online, which I did. Their conclusion was that this seemed like an isolated case and it hasn't been reported in the past. The purpose of visiting the FAA was not to point any fingers, but to document the issue and perhaps prevent this from occurring to someone else. If it happenend to me, there's a good chance it will happen to someone else.
So the moral of the story is: IF YOU SMELL FUEL IN THE CABIN, LAND AND HAVE IT CHECKED OUT BY A MECHANIC. PLEASE DON'T DELAY! I could have easily ended up a statistic in this case and possibly the NTSB would have never known what happened after their investigation since the plane would have most likely burned up after a forced landing in the rugged mountains or rough desert floor.
At every annual, I will direct my mechanic to remove the fire sleeving from this area and check the security of the fuel line on the fuel transducer. After my incident, the MSC advised me they will start checking this on all TSIO-550G engines from now on.
Another tip is to always keep the engine bay and wheel wells super clean, so that in the event there's a new leak of some sort, you'll spot it immediately. I learned this years ago while flying corporate aircraft.