Page 25 - February 2015 Volume 19 Number 2

cold tasks. Use of pre-oilers, pre- heating the engines, and warming the cargo, cabin and avionics fall into the at-the-hangar section. And, finally, monitoring CHT’s, oil pressures, temperatures and delta-P indications, and exercising hydraulic components and propellers, would be in the starting and after-start procedures.Your JetFor the turbine folks that have politely persevered to this point: paraffin, Prist, anti-ice fluids and fuel heaters are cold weather topics associated with your jet. Frozen water in jet fuel can and does clog fuel lines and filters (i.e. British Air flight 38). Like adding a nip of something to your cocoa, Prist, or any FSII (Fuel System Ice Inhibitor) is added to jet fuel in order to achieve an effect. In jet fuel, the desired effect is to prevent water in the fuel from freezing. For convenience and safety, most jet fuel is pre-mixed with an FSII before it’s pumped from the truck; manually adding the proper ratio is not normally required.Delta-P ( ΔP ) is a term that means “different, or difference in pressure” and is normally associated with the pressure measured at the input vs output side of a filter. This can be an oil, air or fuel filter. A caution or warning system alerts us if the delta-p reaches a preset value indicative of a clogged, or clogging, filter. Alternate-air is used to solve an induction-air delta-p, an oil filter bypass valve is for an oil filter ΔP, and a fuel/air heat exchanger is used to manage fuel- filter restrictions associated with ice in jet fuel. The heat exchanger uses warm air on a timer to heat fuel before it passes through the filters. The relatively-warm fuel will then melt ice and any congealed paraffin in the filters (Kerosene is derived from Greek: keros, meaning wax – a component of jet fuel).It’s recommended that oil coolers be warmed before engine start toprevent extreme oil pressures due to congealed oil in the cooler. Oil cooler baffles are typically metal plates installed to block a portion of the airflow through engine oil coolers. Some manufacturers and mechanics recommend them below a certain temperature in order to increase oil temperatures. The baffles assist in achieving normal oil temperatures, which are necessary to both decrease oil viscosity and to boil off water deposited in the oil during combustion. After flying or an engine run, I remove the oil dipsticks to allow some of the remaining moisture to escape as steam.Superior Piloting AbilitiesWe might think that a heated hangar would solve cold weather problems, and that’s mostly true – but we’re back to the “perception of cold” question. How warm do you need to keep the hangar, and for how long before a flight? And a problem actually created by a heated hangar is that snow will melt as it lands on the warm aircraft skin during taxi, and then re-freeze before or during takeoff. Light, dry snow that may have otherwise blown off will “adhere” to the surfaces, just as it does on warm engine cowlings during a quick turn. And that adhere word is one we are not allowed by the FAA. According to the AOPA Air Safety Institute, during the last 10 years there have been at least 25 accidents on takeoff as a result of wing contamination by snow. More importantly than the regs however, is that a contaminated airframe may cause us to need some of our superior piloting abilities – maybe all of them, and we don’t want that.Often, the best option is to heat a hangar to about 50 degrees forseveral hours, followed by the application of an anti-ice fluid if required. Polypropylene antifreeze is pink in color and can be found at RV or automotive stores. A two or three-gallon plastic garden sprayer from the home improvement store works well as an applicator. About four gallons covers the Duke. If away from your home supply of deicer, you may have to purchase aviation Type I, II or IV. Once deiced and anti-iced, if you decide to take off during a snow shower, don’t forget to recalculate accelerate/stop distances using the contaminated runway numbers.FrightfulThere are challenges, tradeoffsand costs associated with coldweather ground operations. Onceyou’ve establish a routine to preparethe airplane, then preheating,applying fluids and referencing anextra performance chart or twosimply adds a bit of time and effortto the launch schedule – it is timewell spent. Your alternative is tostay home in front of that cracklingfireplace with your enhanced cocoa.And when the weather outside isindeed delightful. T&T •frightful, sometimes that option isKevin Dingman has been flying for 40 years. He’s an ATP typed in the B737 and DC9 with 20,000 hours. A retired Air Force Major, he flew the F-16 then performed as a USAF Civil Air Patrol Liaison Of- ficer. He flies volunteer missions for the Christian organization Wings of Mercy, is employed by a major airline, and owns and operates a Beechcraft Duke. Contact Kevin at Dinger10d@gmail.com.FEBRUARY 2015 TWIN & TURBINE • 23