Twin Proficiency: Watch and Learn

Twin Proficiency: Watch and Learn

Twin Proficiency: Watch and Learn

The greatest single advantage of personal air transportation is saving time. Whether you use that time to make money – by beating a competitor to market, serving clients faster, or making more service and sales calls in a period of time – or to improve your lifestyle – by getting back from work in time for family events or creating getaways that could not be done any other way in the time available – you want to (and should) exploit and preserve the efficiency of personal aviation. However, there’s one thing about flying yourself that you cannot afford to skip, even though, in a perfect world, it would be done without your help. You save a lot of time using a personal or business aircraft, but you cannot afford to let fueling operations go unsupervised.

From the NTSB:

During initial climb, the pilot of a Cessna 421C reported a loss of engine power. Unable to return to a runway, the pilot elected to perform a gear-up forced landing to an open field. The airplane was substantially damaged. A line person incorrectly fueled the airplane with 80 gallons of Jet-A instead of 100LL.

Two medium single-engine general aviation airplanes based at the FBO had been modified with turboprop engines requiring Jet-A fuel. The two airplanes were not required by STC to have the fuel filler opening modified, allowing the airplane to operate with smaller fuel filler openings, which did not comply with certification regulations. Line personnel at the FBO discovered that, by rotating the Jet-A nozzle and dispensing at a reduced pressure, Jet-A fuel could be dispensed without using the adapter. Despite having correctly fueled the accident airplane in the past, the line person mistook the accident airplane for one of the converted airplanes and dispensed Jet-A fuel.

The National Transportation Safety Board determined the probable cause of this accident to be: The failure of line personnel to ensure that the airplane was serviced with the proper fuel. Contributing to the accident was the Federal Aviation Administration’s approval of a Supplemental Type Certificate (STC), which allowed an improper fuel filler opening, and the complacency in non-standard fueling practices by FBO line personnel.

Another NTSB report:

The pilot of an E55 Baron departed thinking the airplane had 115 gallons of fuel aboard, when it had 55 gallons of fuel aboard. The shortfall of 60 gallons was the result of a refueling request that the pilot made to a fixed base operator that did not take place and that the pilot did not verify had taken place. Fuel exhaustion occurred in both engines when the airplane was approximately 7,500 feet above an airport. The pilot spiraled down over the airport and entered the pattern for runway 14. He intentionally elected “to err on the side of landing long and not have any risk of being short.” On short final, the airplane was “clearly high and fast, pretty much as expected, but not slowing, which was not expected.” The airplane touched down approximately 1,000 feet prior to the end of the runway, overran the runway end, impacted a concrete irrigation channel about 350 feet from the runway end, and came to a stop approximately 200 feet past the channel.

The National Transportation Safety Board determines the probable causes of this accident to be: The dual loss of engine power due to fuel exhaustion as a result of the pilot’s failure to adequately determine the amount of fuel aboard the airplane during his preflight preparation. A contributing factor was the pilot’s misjudgment of distance/speed during the forced landing, which resulted in a runway overrun.

I’ve had to intervene twice to prevent a fueler from putting jet fuel into a piston-powered airplane. It was the style at the time for manufacturers to paint the word “Turbo” prominently on turbocharged airplanes. A well-meaning line staff saw the “Turbo” and confused it with “turbine”, incorrectly assuming – potentially disastrously – that a turbo airplane takes turbine, or jet, fuel.

Why disastrously? Jet fuel contains far more stored energy than piston aviation gasoline. The spark of ignition in a piston powerplant releases so much energy that the engine itself cannot contain the explosion. It’s called detonation and, as the name implies, it will detonate, or destroy, the engine in very short order. Misfueling accidents involving jet fuel contamination of piston airplane fuel systems, usually cause catastrophic engine failure almost immediately after takeoff.

Misfueling is being investigated as a possibility in the recent crash of a Piper PA46 Malibu Mirage at Spokane, Washington. The investigation has just begun, but responders report “a strong smell of Jet A diesel fuel” at the scene. Kerosene-based jet or diesel fuel has an odor that is very distinct from that of 100LL aviation gasoline. The NTSB has not published a preliminary report as of this writing in early April, but online news sources reported:

Inspectors who responded to the scene of a single-engine plane crash Sunday were concerned the plane may have been flying with the wrong type of fuel, according to a report from the state Department of Ecology. The pilot…crashed his Piper Malibu Mirage [after] just taking off from Felts Field [in Spokane].

Department of Ecology inspectors were called to the scene because of the fuel spill and noted a strong smell of “Jet A diesel fuel” in the air. [An] FAA aviation safety inspector expressed concern that the plane may have been running on jet fuel when it takes aviation fuel. Both types of fuel are sold at Felts Field by…the field’s fuel concessionaire. The National Transportation Safety Board is investigating the crash and has not yet released preliminary findings.

The PA46 is a prime candidate for misfueling, because there are piston versions, requiring the use of 100LL aviation gasoline, and factory and aftermarket turboprop versions that must be serviced with jet fuel. A possible contributing factor: the aftermarket turboprop conversion is done by a firm based at the airport from which the accident airplane departed.

However, any aircraft can be misfueled at any airport on any given day.

Quality Control

There are several reasons to always personally observe the fueling of your aircraft. Greatest among them are to ensure that:

The proper type of fuel is added to the aircraft,

The proper amount of fuel is added to the aircraft,

The fuel is added in the correct amounts in the correct tanks as you’ve ordered,

Your fuel order is carried out at all, and

The proper precautions are observed while fueling the aircraft, including electrical grounding, proper insertion of fuel nozzles into the tanks, prevention of water contamination in precipitation, delaying fueling when thunderstorms are in the area, and re-securing the fuel caps when fueling is complete.

Not all airplane fuelers will be well trained and familiar with the type of airplane you fly. It’s part of your pilot-in-command responsibility to ensure the aircraft is properly serviced. You can’t really do this without personally supervising the fueling of your aircraft.

Putting 100LL Into Turbine Engines

Turbine engines are less affected by use of the wrong type of fuel, but there are adverse effects as well. Notably, most turbine engine fuel pumps and other components are somewhat incompatible with 100LL aviation gasoline. Turbine-engine fuel pumps seem to be especially susceptible to damage from unleaded aviation gasoline.

Consequently, there are limits to the use of 100LL in turbine-airplane Pilot’s Operating Handbooks (POHs). The Beechcraft B200 King Air POH, for example, states:

Limitations On
The Use Of Aviation Gasoline

Operation is limited to 150 hours between engine overhauls.

Operation is limited to 20,000 feet pressure altitude (FL200) or below if either standard boost pump is inoperative.

Crossfeed capability is required for climbs above 20,000 feet pressure altitude (FL200).

It’s obvious that there are some adverse effects of misfueling a turbine-powered airplane with leaded aviation gasoline. It’s not as obvious to confirm that a fuel sample only contains jet fuel. Your only recourse when flying a turbine-powered aircraft is to watch the fueling process.

Detecting Misfueling

If, for any reason, you suspect the quality of the fuel you have added to your airplane, it’s easy to detect jet fuel in aviation gasoline. The easiest way to check for Jet-A in 100LL is to dribble a little fuel onto a card or a paper towel. The sample should dry quite rapidly. If it’s dry after two or three minutes (perhaps leaving a blue stain), it was 100LL and you are good to go. If the card or paper towel is still damp and oily, it is at least partly jet fuel – and it’s time to call a mechanic to de-fuel and decontaminate the airplane.

Some commercial products will warn of jet fuel contamination. For example, the GATS fuel jar instructions suggest using the differences in evaporative properties between 100LL and jet fuel as a test every time you check the fuel sumps. According to the instructions:

To test for jet fuel contamination, coat the separator screen with the fuel sample. This is done when the extracted fuel is returned to the aircraft fuel tank. After emptying the tester, turn the screen upright, so it can be blown on gently at a distance to avoid breathing in gas fumes. The heat in the exhaled breath will evaporate the AVGAS within roughly 30 seconds, regardless of the ambient temperature. AVGAS alone will leave the holes of the screen empty and the screen looking dry. Jet fuel, if present, will remain in some of the screen holes….

The GATS jar is widely available at pilot supply shops.

Watch and Learn

To confirm that the proper type of fuel is loaded in the proper amount in the proper tanks, and that the fueling process is done properly (i.e., electrical grounding, observing airplane limitations), it’s necessary to personally watch the fueling process. Perhaps you’re in a hurry to get to a business meeting, respond to a company crisis, or whisk your family or guests to that vacation destination. If you don’t have time to watch the fueling process when you arrive, tell the FBO you don’t want any fuel until you return. Plan to arrive a quarter-hour early to personally observe the fueling process when you depart. If you don’t want to keep your passengers waiting, make an appointment to meet the fuelers during your stay, while your passengers do something else.

Your pilot-in-command responsibilities don’t start when you board the aircraft and end as the propellers or turbines come to a stop. It takes a little time before and after a trip to ensure the airplane is ready for flight. One of the most important things you must do as pilot-in-command is guarantee you have enough of the right type of fuel in the tanks. Only by watching the fueling process can you learn whether it’s being done correctly.

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