Page 16 - Nov 2015 Volume 9, Number 11

the passengers second thoughts about the safety of their transport since they’ve been taught that “Where there’s smoke, there’s fire.”
Recognizing the detrimental effects of allowing the fuel to dribble through the nozzles, turbine engine engineers have made provisions to eliminate this condition. In the Pratt & Whitney PT6, starting right from day one, the engines have incorporated a Dump Valve. This device – between the FCU and the manifold(s) feeding the nozzles, often right on the manifold – is held closed by positive fuel pressure, but opens due to spring force at shutdown when fuel pressure drops. It provides a path of lesser resistance allowing the last bit of fuel to dump harmlessly out of a vent tube onto the ramp. With that easier option available, no fuel dribbles through the nozzles since there is an easier way for it to escape.
The first 10 years of King Air production – like all other turbine engines of the time – had fuel venting onto the tarmac at every shutdown. How much? About a half-cup (four ounces) typically. The Environmental Protection Agency (EPA) was created in 1970 during the years of the Richard Nixon administration and one of its early directives was that all this dumping of raw jet fuel onto the airport ramps and then evaporating into the atmosphere or being washed into the storm sewers could not be a good thing for Mother Earth and her inhabitants. It had to be eliminated.
The King Air model 200 – the best seller of the entire series – was in its certification flight test program from October 1972 to November 1973. Facing the coming EPA mandate, Beech was working to incorporate a new shutdown fuel purge on this airplane. Nearly the entire Beech factory workforce was permitted to leave their normal posts and to move out by the runway at Beech field when the prototype, BB-1, made its maiden flight on October 27, 1972. We watched the white plane takeoff and were there for the landing about 45 minutes later. Ah, success, as the plane taxied up to the parking spot near where Mrs. Beech herself, Chairwoman of the Board, and Frank Hedrick, President, were waiting. As the engines spooled to a stop, it was a bit nerve-racking to see tons of white smoke pouring out of each set of exhaust stacks. Hmm, we all thought, are we going to watch BB-1 go up in smoke after just one flight?! The smoke eventually stopped and the engineers went back to their desks for a little more attention to this area of concern.
The system that was perfected and installed on all early 200s quickly made its way onto the other models of King Airs that were being built. Serial number LJ-672 in the C90-series, LW-124 in the E90-series, and B-208 of the A100-series were the first King Airs, other than the 200 model, to have a factory-installed “Fuel Drain Collector” system. Beech offered a kit to add this system to earlier models to bring them into compliance – known as the “EPA Kit” – and some operators got field-approvals for systems of their own design. This all happened in 1975.
The Beech system is comprised of the following elements: (1) a metal, rectangular, collector tank big enough to accept about 20 ounces of fuel, mounted on the lower portion of the aft cowling fire seal; (2) an Up-On/ Down-Off float switch installed in that tank; (3) a line going from the tank to a pump; (4) a small electric fuel pump mounted in the cowling near the tank; (5) a line, containing a check valve, going from the pump back into the nacelle fuel tank; and (6) a vent line from the top of the collector tank going to a universal drain tube that vents (don’t tell the EPA!) onto the ramp.
The new fuel drain collector pump needed a power supply. It was found that the Fuel Control Heat circuit breaker/switches had enough unused capacity that the power for the collector pumps could be forthcoming through the respective side’s Fuel Control Heat switch. Since the switch is normally off prior to shutdown, the half-cup of fuel sits in the collector tank after shutdown. It does not get pumped into the nacelle tank until the Fuel Control Heat switches are turned on following the next start. This causes no problems whatsoever, so don’t buy into the misinformation that you should leave the switches on until after shutdown.
Beginning with serial numbers LJ-738 and LW-248 in 1977, Beech stopped wiring the collector pumps to the switches and began having dedicated left and right Fuel Drain Collector CBs installed on the cockpit’s right sidepanel. This is also the case with the F90, the LA-series that appeared in 1978.
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14 • KING AIR MAGAZINE
NOVEMBER 2015