A light bulb goes on: warming up to a good idea
February 2, 2009 by Dave HirschmanStarting a cold-soaked piston aircraft engine can seem cruel and abusive. The battery protests, the starter groans, cylinders fire reluctantly, and the needle on the oil pressure gauge takes its time coming to life.
All that metal-on-metal contact during the first few seconds of cranking can cause significant wear—some say as much as hundreds of hours of normal engine operation—and no one wants to face an early engine overhaul.
FBOs will gladly pre-heat your engine—for a price. The going rate in the Mid-Atlantic is $25 for a single and $30 for a twin (don’t ask why the disparity). A variety of propane, kerosene, and electrical aircraft pre-heaters are available for aircraft owners to buy and use themselves. Prices range from about $150 for a plug-in pad that connects to your oil sump; to $300 for a modified kerosene heater that blasts hot air into the engine compartment; to $470 for a small, cleverly modified, omnivorous camp stove that burns everything from Coleman fuel to avgas, is small enough to bring along, and doubles as survival gear in remote areas.
But for the ultimate in frugality, it’s hard to beat a light bulb.
A fellow pilot in a nearby hangar has an old-fashioned desk lamp that he converted to an engine compartment heater by simply removing the shade (and adding a shroud to prevent the bulb from becoming a fire hazard). When he’s finished flying, he covers his airplane’s cowl with a thick blanket, plugs the air intakes, and positions the lamp so that its single, 125-watt bulb reaches up into the engine compartment below the oil sump.
By simply leaving the lamp on, heat from the bulb does a remarkable job of keeping the engine warm, even on freezing winter nights. And the next time he starts his engine, the oil is typically more than 20 degrees warmer than the outside air, and the oil pressure needle in the cockpit registers instantly. Even the cost of the electricity is covered as part of his hangar rent.
Of course, light bulbs are no match for the brutal winter temperatures in far northern latitudes. And no bulb works as well as a purpose-built pre-heater designed to raise engine oil temperatures 80 degrees Fahrenheit above the outside air. Lycoming says its engines should be pre-heated when the mercury falls to 10 degrees F (20 degrees for some models) or below. But why wait until it gets so frigid?
Winter mornings here in the Mid-Atlantic, for example, are often around the freezing point. If plugging in a reading lamp is enough to keep the engine oil in the 50s, it seems like a good idea.
In fact, isn’t a light bulb the very symbol of a good idea?
February 6th, 2009 at 5:17 am
I use an electric 250 W modified soldering iron. I removed the bent copper soldering tip and replaced it with a straight, long, tip of copper. On this copper bar I, welded “wings” of copper sheat so it will fit into the exhaustpipe. These wings will hold it in position inside the exhaust pipe. 250 W of heat will then go from the exhaust pipe up to the engine and keep it warm enough for a smooth start.
This solder, after cooling down (I dip in the snow) can easely be carried in the luggage compartment plus a long cable for the power outlet.
February 6th, 2009 at 7:38 am
The essential part of the preheat process that is under emphasized is the need for good insulation. Almost any heat source, even the light bulb, will do a fine job given enough time AND enough insulation to keep the heat in the engine compartment. Worse, failing to insulate will lead to non-uniform warming which will leave cold spots on the engine. Cold metal at a temp below the dew point will provide a place for condensation occur. Inside the engine that is not welcome. So wrap it when you heat it. Additionally, keep in mind that to be kind to your engine you should try to imagine the temp of the crankshaft, a massive piece of metal at the heart of the engine resting in cold bearing surfaces. Be at peace that you have done a good job of preheating if you can visualize that the heat has migrated to this vital and vulnerable area. In other words, don’t rush it.
February 6th, 2009 at 8:11 am
If the airplane is in a remote enough place where there is no electricity available, using the exhaust from your car will make the engine compartment as warm as toast, in 20 minutes if it is covered with a heavy blanket. The hose must be able to withstand the heat of the exhaust of the car. The type that auto repair shops use is best. While 20 minutes may not warm the crankshaft much, it will definitely make for an easier start. Better than nothing.
February 6th, 2009 at 9:17 am
Living and flying in Buffalo NY requires some extraordinary actions to prevent no go issues precipitated by cold weather. If the temps are scheduled to be below 20F I have a pair of quartz heaters which I rest on the props of my Baron and blow warm air into the nacelles which are covered with some quilted furniture pads long ago expropriated from a moving company. In addition, I hang a 100 W light bulb under the instrument panel to help keep the instruments warm. I also keep a bottle of water in the airplane. If it is frozen then I have a pretty good indication that the airplane is too. When it is to be really cold I take the batteries home and leave them in the back hall so that they are warmed up and have full cranking power. It takes about 10 minutes longer to get the airplane ready for flight but at least the engines are warm, the instruments are not going to be shocked by spinning up with the potential of even a small ammount of frozen condensation inside, and the batteries are 100%. This way, I can spend most of my energy digging out the snow from in front of the hangar door.
February 6th, 2009 at 9:38 am
So at 10 cents per kilowatthour (the National average is 10.68 cents, see http://www.neo.ne.gov/statshtml/115.htm for a state-by-state breakdown), to keep a 125 Watt light bulb burning constantly costs 30 cents per day, $2.10 per week, $9.30 per month, or $109.50 per year. That’s a good deal!
February 6th, 2009 at 11:10 am
I am a California pilot where a cold day is around 70f
. Seriously, something I figured out and use helps saves batteries when doing a cold weather start. Instead of priming when the check list says to prime, do it first thing, before doing the walk around. When starting the engine, skip the priming procedure because you already did it. Doing early priming on cold days I find that the engine kicks over and starts in a few cranks. The likely reason this works is fuel vaporization. Engineers tell me that engines do not fire if the fuel is liquid or atomized; it has to be vaporized. On cold mornings leaving the priming charge in the manifold for several minutes before the start gives time for vaporization to occur.
When I am out on our field (Palo Alto, CA) on cold morning I hear the long slow crank grinds of pilots who didn’t do an early prime and all I can say is ‘poor battery’.
Disclaimers:
I have tested this on the SR22, C206, C182, C172 and Piper products of various sorts. This really makes a difference in starting larger, high performance engines.
I have employed this technique with good results with temperatures down to slightly below freezing (this isn’t Minnesota
I have not tried it on a pre-heated engine, light bulb or otherwise.
This technique obviously has nothing to do with high oil viscosity due to cold engine temperatures on start.
I have written in more detail on this topic on my blog site: http://www.davesflightnotes.blogspot.com. See ‘Be Nice to Your Engine’.
February 6th, 2009 at 11:28 am
I have been using a 100W light bulb in one of those shop lights that come with its own cord and has a hook on the bulb cover. I use a blanket with bungee cords around the cowling and foam plugs in the air inlets. The oil stays warm and the engine starts fine. The only problem I’ve had with leaving the light on all the time is the bulb burning out. I live close enought to the airport in the Front Range of Colorado, that I will run to the airport the night before or ~4 hours before I anticipate flying and plug in the light. My plane is a 1946 Piper PA 12 – Super Cruiser.
John
February 6th, 2009 at 11:58 am
John Miller, barnstormer, published the electric light –cowling in the engine compartment method in American Bonanza Mag several years ago. (Miller died at the age of 102–in bed). He said with this 24/7 method of heating engines all of his engine went to TBO. Miller himself went beyond TBO. I changed his method to the 100 watt ceramic heater up the exhaust. Light bulbs, even halogen burn out too fast. I measured temp. relative humidity and found when the engine was covered temp was increased over ambient and humidity was reduced in the crankcast.
Humidity is the highest between 5-7 am, temperature due pont spread is the narrowest.
February 6th, 2009 at 12:07 pm
I use a $10 hair drier to heat the cylinders on my Jabiru. 20 minutes per side does it I leave the plugs and cover on. If you don’t have electricity where you are, Walmart and others sell 1500W generators for $149. They are just adequate.
My engine starts on the second blade. The oil temp needle is already off cold.
February 6th, 2009 at 12:40 pm
Just a word of caution. A friend tried this on his automobile. Oil on the engine block caught fire. Things really got warm. Rocco’s suggestion about the ceramic heater is a better idea, at least they don’t break as readily J.
February 6th, 2009 at 12:49 pm
I live in the Northwest where it is generally cool and damp. I keep my aircraft in an un-heated hanger or if it is full (I do aircraft inspections and repairs) I have to leave it outside. I have found out over the years that there are 2 things that will decrease the life of the engine, electronics and interiors and that is moisture and cold. If the temp gets below about 50 Degrees and you have high humidity then it will collect moisture on engines, avionics and interiors (internally and externally). I keep a controlled heater inside the aircraft and a pan heater on the engine of my Comanche at any time the outside temp gets below 55 deg. I set the cabin heater for approx 55 degrees. You can get one of these temperature controlled heaters at Wall Mart for approx $20, follow the instruction on proximity to cabin parts.
I have found out that there is no moss forming in the inside of the aircraft, electronic problems are eliminated (moisture forms on the inside of radios and can corrode and short out internal parts when high humidity is present and power applied). When I pull the plugs of a non heated engine, when it is cold they are usually wet which is a sign that the whole inside of the engine is damp which is very corrosive. When the engine is kept heated the moisture does not collect and it does not collect moisture under or in the oil. If the engine in intermittently heated and cooled the moisture will develop and the advantage is lost. If you keep the engine warmer than the outside and above 50 degrees moisture will not form on the metal parts and moss will not get hold of the inside of you aircraft, even after long spells on non activity. I have flown my Comanche for approx 15 Years and have never had electronic problems. Dew does not form on the inside of my instruments to cloud and corrode them. These problem occur when the aircraft is either outside or in an un-heated hanger.
The cost of operating and purchasing these are is generally less than one trip to the avionics or FBO shops for repairs.
Happy safe flying.
Dave
February 6th, 2009 at 1:19 pm
I installed a Reiff heater, 500 watts total just before relocating to Michigan. It is not uncommon for the engine monitor to show EGT and CHT readings of 70 plus degrees before starting, even on the coldest days. I usually turn the heater on for 6-12 hours before flight by using a timer. I use a ceramic heater under the dash, also on a timer. I don’t think there is a “quick answer” to engine preheats. (I thought I was the only one who visualized the temperature of the crankshaft when determining an engine’s readiness to start!)
There is a time to think about time, and a time to think about money. Don’t spend thousands to save an hour. Heat it up right, whatever method you use.
February 6th, 2009 at 1:26 pm
A device which has been around for many years for warming automobile engines called a dip stick heater and available online or at automotive parts stores has dependably warmed my C182 engine oil and engine for years.
The evening before a planned departure, I go to my hangar and go through the maps etc.,, check over the plane, take out the dipstick and replace it with the dipstick heater and plug it in. I then cover the cowl with an old mattress cover and an old sleeping bag and in the morning the oil and engine are nicely warmed.
One strong warning! I have been told that if one leaves a dipstick heater in the oil for an extended time, it will form a coating of carbon around it making it impossible to remove. I never leave it for more time than just overnight and also don’t touch the end, it gets hot!
Also make sure the dipstick heater is near to the same length as your dipstick so the end will be in oil.
I also use the light bulb under the panel trick, the gyro is much happier starting when it is a little warm, it spools right up.
Before the dipstick heater, I used a flexible metal pipe up the exhaust heated by a propane torch at the other end, but always in my presence, and beware of the fire danger, It is portable and provides a lot of heat fast. Turning over the engine some by hand will also open other valves distributing the heat better.
I really like the car exhaust idea when there is no power, but I would not do this in a closed hangar due to the possibility of CO poisoning.
February 6th, 2009 at 2:56 pm
Not only will your engine and panel instruments appreciate the nice warm environment so will any mice that happen to find their way anywhere near the heat. Believe me those little buggers can and will find their way to your warm snuggly abode. Check carefully for them.
February 6th, 2009 at 6:36 pm
I have used a air popcorn popper in the Northern climates of Minnesota. Works great!!
February 6th, 2009 at 6:51 pm
My C-152 is kept in a closed but non-heated hangar, for many years I have used the 24 inch Goldenrod de-humidifier in the cabin to prevent condensation. The purpose is not to heat the cabin but to circulate the air. This works for me. One of many suppliers is: http://www.goldenroddehumidifiers.com/models_specifications.htm# (OR Google GOLDENROD). For engine preheat I installed the HotPad on the oil sump, after 30 minutes heating the engine is ready to start.
February 7th, 2009 at 10:15 am
Yet another cheap solution I’ve found is this: I have a small ceramic heater with a dryer duct attached to the front, which is then routed into the lower cowling of my 172. I add a couple blankets over the cowling, cover the air inlets, and plug the heater in a couple hours before a planned start. This method heats the entire engine compartment quite well, and the airplane starts quite easily. I generally use this method anytime the temps fall below 35-40 F.
February 7th, 2009 at 2:25 pm
Hello Aviators:
During a year spent in North Western Ontario over the winter I was in command of a Navajo Chieftain. Part of my responsibilities was making sure my aircraft was always ready for use for Medivacs on short notice. During a particularly cold day, -42C, I removed the two automotive block heaters from each engine Nacelle, along with the engine covers, scampered back into the cockpit and started the engines, I had positive oil temps and instant oil pressure on both engines. It was wonderful to know the engines were properly warmed up before starting.
I would recommend this set up to any one.
At that point keeping the interior was more difficult.
February 7th, 2009 at 8:44 pm
Sounds like there as many different solutions as there are pilots. The light bulb trick has been around for years as a way to make sure the car starts on cold mornings in sub zero temps. I have a 100 watt bulb in a cheap reflector base with a clamp that I put in the engine compartment of my Archer, along with the blankets and plugs others have mentioned. In addition I bought a small Coleman propane heater. Setting that face up with an 8″ x 4 foot piece of flexible aluminum vent pipe ducted into the front of the engine cowl inlet, with an additional piece of 3″ tubing cut into the 8″ pipe and directed up the exhaust stack; provides lots of heat while doing the preflight and makes for quick starts.
February 8th, 2009 at 1:17 am
A ceramic heater connected to 4″ flexible aluminum dryer vent ducting routed into the cowl flaps along with a cowl blanket consistently results in our Skylane starting in one second or less. The engine instantly idles as if it had been running for several minutes. Another small thermostatically controlled heater in the baggage compartment keeps the entire cockpit, starter battery and instruments nice and toasty despite below freezing temps. To save electricity I use an AC timer to kick the units on a few hours before I get to the hangar.
I tried the light bulb techniques but did not have much success in our sub-freezing temperatures.
February 8th, 2009 at 10:50 am
I used the Non-hanger approach on a cold morning.@ 20 min. pre – flt warm up W/ 3″ flex metal pipe and a bunge (to hold in place)to truck exhaust.
Shure would like 2 know a solar to heat frugal combination for us poor ramp tie down slum pilot owners. So far I have a solar trickle charge 2 battery then what? Maybe a modifyied window defroster. Automotive seat heater element from a junk dealer.
We all know it is just a little bit that helps.
February 9th, 2009 at 4:12 pm
Luckly, I live in the south and once every few years a cold start is a major consideration. I do not want to rain on anyone’s parade but I would like to suggest we think about light bulb pre-heating. Nearly all my flying is in antiques, some of which still use a tapered cork in the fuel shut off valve. Also, a radial will leave a quart of oil EVERYWHERE behind the accessory case after a few hours of flying. Do you really want to put a hot bulb at the lowest point in an engine’s cowl where oil and possibly gasoline might drip on it? I have a vivid picture of oil/gasoline dripping on the bulb and steaming up, while some runs down the bulb’s stem and into the socket. Probably the bulb is safe while its glass envelop is whole, but the dripping might cause the envelope to crack, and give a spark when the filament is exposed to the air. Secondly, if you have a stand alone hanger and it burns up, it is a tragic loss. It you are in T hangars and your fire is responsible for burning up 20 other planes; I hope you have $2M+ in insurance! I would suggest that an aircraft insurance person be brought into this discussion, as well as the AOPA legal eagles.
February 21st, 2009 at 10:18 pm
For the non-hanger group and those with no car support at remote airports, I’ve used an MSR camping stove which can run on 100LL, a 6″-4″ aluminum reducer and a 4″ aluminum flexible dryer duct directed into the bottom of the cowl. With the cowl insulated/covered and the nose plugs in, it will warm up the oil, induction and cylinders in 20-45 minutes (depending on temperature, wind, etc). No electricity or car required, and its small and light enough to take on any airplane. As with most fire based preheating solutions, keep your fire extinguisher handy.
February 27th, 2009 at 2:47 pm
Better buy a lifetime supply of those light bulbs now!
They are on the environmentalist’s agenda! (ban already enacted, but not yet in force)
April 2nd, 2009 at 8:25 pm
I dont usually comment, but after reading through so much info I had to say thanks
June 27th, 2009 at 1:24 am
Engaging content- will definitely come back again=)
July 12th, 2009 at 10:58 pm
I have used a $25 Kats model 24150 heater from Northern Tool on airplanes with good success. It is only 150 watts, but in an unheated hangar and with an old quilt over the engine cowl it works well, even in frigid Minnesota. My IA checked with the local FAA office and they said its okay, although the purveyors of expensive aicraft engine preheaters claim this is illegal.
August 12th, 2009 at 3:59 am
Really useful information.Thanks for providing information on A Light bulb goes on : Warming up to a good idea.
August 14th, 2009 at 8:55 am
Starting a fire under a fuel source seems not a good idea. I would be extremely cautious (read – would not do) about using a light bulb under an engine. It can heat up fuel in the float bowl of the carb and start a fire. It can set off any fuel – liquid or vapor – and start a fire. It can start afire without a match so well the Boy Scouts may start using it.
Non flame heaters make more sense than anything else. Conducting heated air is safer than direct radiant heat from a bulb or flame. Heated air is more diffuse and less concentrated. – more gentle on the engine. It flows around crankcase and jugs, filling an engine bay with heat.
I hadn’t thought of damage from humidity collecting inside the cockpit. DARN! Thanks for the tip on that one!
August 23rd, 2009 at 4:46 pm
I have a Reiff sump heater. When I am away at an airport on the ramp, I start up my 30lb Honda generator (mine’s a 600 watt, the new ones are 1000) and let it run. If I’m afraid of it coming up missing, I use a cable and padlock to attach it to the wing strut. It will run for 5 or 6 hours and my engine start’s great!
September 18th, 2009 at 10:36 am
We use custom engine covers, with a Tanis oil sump heater here in Cleveland. I control the heater operation with an in-line thermostat.
I plug the heater into the thermostat and set it for 60 degrees and stick it in the oil filler opening and install the covers. 60 degrees is maintained, nothing more nothing less. Monthly electric bill during the dead of winter is $20