Mooney: Engine Failure on Take-Off
I was looking for something else entirely when I found the docket for this case, a Mooney crash in 2004. The NTSB report is only six pages and most of that is the standard form and bad pagination. I wouldn’t normally bother with a crash this simple but I found it intriguing how the docket information gives an insight as to the progress of the investigation.
The pilot had 656 hours total with four hours in the last 30 days, a pretty typical private pilot. He was rated for single-engine land planes and was instrument rated. The aircraft was a Mooney M20J, registration N302SB, with 4,500 hours.
The 11th of July 2004 dawned clear with calm winds, blue skies and ten miles visibility, a perfect day for flying. The pilot was departing from Hackettstown, New Jersey, a general aviation airfield with a 2,200 foot asphalt runway. The airfield elevation is 670 feet above sea level.
The previous day, the pilot had refuelled at Lawrence Municipal Airport (LWM) in Massachusetts and flown to Hackettstown Airport, where he spent the night.
He returned to Hackettstown Airport the next morning. At about 7am local time, he departed the airfield to return to Lawrence Municipal Airport. He took off from runway 23. However, as he reached about one hundred feet above the ground, the engine lost all power. The aircraft struck the rooftop of a house and crashed into the trees of their garden, about 200 feet past the departure end of the runway. The pilot suffered only minor injuries but the damage to the aircraft was substantial.
Here is his initial statement to the NTSB:
I went to the aircraft at approx 6:30 am EDT and performed a complete pre-flight and run up of the aircraft. Fuel was at 3/4 full and I did not take on fuel since leaving LWM the day before. Immediately after rotation, at an altitude of approx 100 feet above the runway, the engine quit. I switched tanks and lowered the nose and attempted to restart the engine. It did not restart.
The plane landed on the roof of a house and came to rest in a tree. I was able to get out of the aircraft myself. I was departing Hackettstown NJ N05 at approx 6:50 AM with LWM as my intended destination.
The wreckage of the aircraft and the engine were examined by an FAA inspector, who could not see any sign of pre-impact mechanical malfunctions.
Compression was attained on all cylinders. Valve train continuity was observed, and crankshaft rotation was verified. When rotated by hand, the single drive dual magneto produced spark at all lead ends. The top spark plugs were removed for inspection. Their electrodes were intact, and were light gray in color.
The owner of George’s Body Shop in Hackettstown was on site to help with the clean-up. He drained approximately 20 gallons of 100LL fuel out of the right fuel tank and “about nothing, maybe 4 or 5 gallons, from the left.” Whether or not the pilot did, in fact, remember to switch tanks, it certainly seemed to me like if he was set to the left tank for take off, he may have starved his engine of fuel because his fuel was balanced incorrectly.
However, the reality was simpler than that.
The inspector pulled out the fuel pump, which was in perfect working order. But when he manually [manhandled] the fuel pump, water spilled out of the fuel outlet port. He also found water in the gascolator (the fuel strainer). When he tipped it out, it came out to about six ounces (175 ml) of water.
Water can condense and accumulate in fuel tanks. A part of the pre-flight check is to check the sump drain, which is located at the lowest point in each fuel tank. When the fuel is all shaken up, it doesn’t do much good to take fuel from the sumps. However, after the aircraft has been sitting overnight, the water will settle at the bottom. This is why, as a part of the preflight checks, the pilot drains a small amount from the sump drain to verify that what he is seeing is, in fact, fuel, as a part of a standard pre-flight check. If there’s a small amount of water, you can usually just quickly drain it out using the sampler, as long as the second sampler from the sump is fuel. The sampler I used on the Saratoga was 50ml, about 1.6 ounces. Six ounces sounds like a lot to me and more than I think I’d be happy with finding in my sump checks.
This means there are two logical conclusions that can be made. The first is that there was enough water in the fuel to block the fuel flow, feeding water to the engine instead of 100LL, which doesn’t do anyone any good. The second is that despite the pilot’s report, he did not do a thorough preflight check. He did not check the fuel sumps. It turns out the Mooney also has a drain valve installed in the fuel selector valve assembly, which allows you to drain the lowest point in the fuel lines. He clearly didn’t drain this either.
Occurrence #1: LOSS OF ENGINE POWER(TOTAL) – NONMECHANICAL
Phase of Operation: TAKEOFF – INITIAL CLIMB
1. (C) FLUID,FUEL – CONTAMINATION,WATER
2. (C) AIRCRAFT PREFLIGHT – INADEQUATE – PILOT IN COMMAND
Occurrence #2: FORCED LANDING Phase of Operation: DESCENT – EMERGENCY
Occurrence #3: IN FLIGHT COLLISION WITH OBJECT
Phase of Operation: DESCENT – EMERGENCY
3. OBJECT – RESIDENCE
4. OBJECT – TREE(S)
The NTSB declared that the probable cause of the accident was the pilot’s inadequate preflight inspection, which resulted in the total loss of engine power due to fuel contamination, during the initial climb after take off.
That’s the important point: the cause was not that there was water in the fuel, because it is impossible to guarantee that water won’t condense in the fuel tanks overnight. The real failure was not to check for it. Draining fuel from an aircraft is a trivial exercise. Recovering an aircraft in this state is an impossibility.