What Warmup Procedures Would You Recommend for Winter Flying?

6 Answers

1. 
   

   
   

   Wesley Beard on Feb 18, 2011

   Most pilots will wait till the oil temperature is in the green arc before taking off.  It is quite possible to have to sit on the side of the runway with a higher than normal RPM to get the oil temperature into that range.
    
   The biggest concern with winter flying on the engine is the start.  On really cold days, it is going to take a healthier battery (don’t know the correct term here) to provide the amps necessary to turn the starter and sequentially the propeller.  The oil is also thicker and requires extra energy to move through the system.
    
   Most aircraft owners who are particularly worried about the cold mornings will have a engine heater installed in the cowling.  They can simply plug the heater in and the engine will warm up to a set temperature making the engine start easier and last longer.

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2. Best Answer
   
   

   
   

   Steve Pomroy on Feb 18, 2011

   Hi Roland.
    
   +1 to Wesley’s post.  The actual start is the hardest part of of the flight for the engine.
    
   You probably already know this, but the first place you should go for information is the flight manual for your manufacturer’s recommendations/requirements.  In the aircraft I fly these days, we have published low-end oil temperature limits — 5C to start the engine, 40C to exceed 1500 RPM (for runup or takeoff).
    
   In the absence of manufacturer’s input, there are a few rules of thumb to use.  First, in extreme cold, pre-heat the engine using a heater and engine tent.  If the aircraft has a block heater (not very common, but they’re out there), use it.  After the engine is running, let it sit at low RPM for several minutes before applying even enough power to start taxiing.  Set the RPM high enough to minimize plug fouling (~1,000 RPM), and let the engine and oil warm up for  awhile.  This doesn’t take long.  By the time you’ve got your post-start checks done, you shoul d be ready to taxi.  Once you’ve taxied to your runup spot, don’t actually start the runup until the oil temp needle is at least “off the peg”, and prefereably into the low yellow if the gauge includes a low yellow range.  Finally, for takeoff, you want the oil temp in the green.  In very cold weather, that might mean doing an extra long runup.
    
   Cheers,
   Steve
   http://www.flightwriter.com

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3. 
   

   
   

   MaggotCFII on Feb 18, 2011

   Preheat the engine.
   Our company rule is to preheat below 32 degrees.  We use the propane forced air portable units, use the cowl plugs and a blanket over the engine.  Ducting (2) are positioned to warm the oil sump and the cylinders.
   At 32 degrees about 20 minutes suffices – colder longer.
   The airplane has been pre-flighted and ready to start.  However, no person is in the airplane during the preheat and the PIC has the key in his pocket.
   When the ducts, cowl plugs and blanket are removed and ground handler are clear.  We board to start.  After saying a big “Thank You” to the ground crew!
   The airplanes with the electric heaters, Tanis, etc. do well after three hours at the 32 degree point – actually nice and toasty – one just has to remember to ask the ground guys to plug things in well before the drive to the airport.
   After start needle off the peg for taxi and in the green for take-off.
   Your FBO should be a good source for “local customs” for preheat.
    

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4. 
   

   
   

   Earl Kessler on Feb 18, 2011

   One of my students has a Diamond Star DA 40 with an electric block heater, and an electric portable heater in the cabin.  Warming your instruments is equally important to keep them from excessive wear when stone cold.  He has a phone line connected to his hangar and a device connected to his electric plug that he calls remotely and it turns on both.  He usually calls them (depending upon the temperature) anywhere from 2 to 4 hours before launching.  In addition, he has a battery tender (trickle charger) plugged into the battery to keep it fully charged prior to start.  It makes that first golden 5 minutes after start a period that doesn’t cause undue wear on your engine and gauges.  Another trick is keeping a blanket over the cowl and even leaving an incandescent bulb turned on below your cowl.

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5. 
   

   
   

   Kent Shook on Feb 19, 2011

   Steve,
    
   Great answer, but where are you? Here in Wisconsin, nearly every airplane has a Tanis or Reiff heater. The Reiff heater (with cylinder bands) and a pair of good-quality cowl plugs makes a an excellent combo – I even put my hands inside the oil door to warm them up on a cold preflight!
    
   We plug the heaters in any time it’s below 40ºF, and if the engine is not warm, we require a preheat below 20ºF. No touch and goes below 0ºF, and no operation whatsoever below -20ºF.
    
   From a cold-soaked engine, it can take up to 8 hours, or even more, to get the engine warm enough to start safely. Use your judgement – If you have crappy (or no) cowl plugs and the airplane is facing into a stiff wind, you may just want to get a butane preheat from the FBO. 
    
   On some airplanes, the oil temp gauge will not even come off the peg even after extended operation on the ground. Use your judgement. If it’s REALLY cold, you may need to idle for up to 10 minutes, then do another 10 minutes at 1000 RPM prior to doing your runup. You can help the warming process by NOT facing into the wind at all, if there is any and you can help it. Make very slow throttle movements, and listen carefully to the engine for any abnormal noises. Note the oil pressure during your runup, and when you’re done, slowly advance the throttle to full power while watching the oil pressure carefully. If the oil pressure is in the green at full power, you’re warm enough to go.
    
   Note that you may also need some different techniques to get the engine started in the first place. I’ve had situations where it was so cold the engine wouldn’t start without the carb heat on, possibly due to an iced-over air filter. I had to let the engine warm up for 10 minutes or so before it would run with the carb heat off. You may need to prime a lot. Not to toot my own horn, but we had an episode of the Pilotcast with an A&P talking about this very subject – Check it out here: http://pilotcast.libsyn.com/pilotcast_018_2005_12_21 (click the “POD” icon to the left of the title, or the “direct download” link at the bottom.)
    
   Finally – DO carry survival gear. If you lose an engine enroute, you need to be prepared to spend several hours or an overnight outside in whatever weather you’re flying in. I generally not only dress warmly, I also throw a winter sleeping bag in the baggage compartment. A GPS PLB is also a big help to get rescuers to you more quickly.
    
   There’s lots to learn and consider, but the payoff is big: Airplanes LOVE flying in the cold air. It’s quite fun to just do pattern work, and reach pattern altitude before you’re even at the end of the runway. VFR weather in the winter generally means EXCELLENT visibility. Night flying with snow on the ground under a full moon is one of my favorite things – It’s beautiful, and you can see everything as if it was daytime.
    
   Enjoy, and fly safe!

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6. 
   

   
   

   Steve Pomroy on Feb 21, 2011

   QT:  “Great answer, but where are you? Here in Wisconsin, nearly every airplane has a Tanis or Reiff heater.”
   Hi Kent.
    
   I’m assuming you’re asking that because of my comment about the block heaters being uncommon.  And sure enough, in my own experience they are.  To be honest, I’ve always wondered why…
    
   Nowadays I’m in Manitoba.  But in fairness to the locals, I’m new to the area, and it’s entirely possible that everyone around here has block heaters (they do in the cars, and most parking spots have electrical outlets for them).  My employer doesn’t use them, but our airplanes are always in warm hangars overnight, and there isn’t much downtime between flights.  We just use cowl covers if there’s to be a break between trips.  On the rare ocassion that an engine cools down too much between flights, it either goes back in the hangar or gets pre-heat from a propane blower.  But that’s uncommon enough that I haven’t seen it in the time I’ve been here (5 months now, 3 of which have been winter).  Our biggest problem shows up on first launch of the day, when we often have to wait some time to get 40C on the oil temp for the runup.
    
   Most of my previous life has been spent in the Atlantic region (mostly split between Newfoundland and Nova Scotia).  I think I saw a grand total of one block heater on a flight school aircraft, and a small handfull of others on privately owned aircraft.  Like I said uncommon in my experience.  But it seems to me that if I owned an aircraft or ran a flight school, it would be a worthwhile investement.
    
   Cheers,
   Steve
   http://www.flightwriter.com

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