Ted
The pilot formerly known as Twin Engine Ted
- Joined
- Oct 9, 2007
- Messages
- 29,997
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iFlyNothing
As long as there have been fuel injected aircraft engines, there have been arguments on the best way to hot start the things, and the primary consensus is that hot starting them is annoying, and for many, relatively inconsistent. You've probably heard dozens of techniques for hot starts, you may have tried them, and you may have found that some of them work, but not very well. Maybe you've found one that works on your plane, but not on others. Certain aircraft engines have minor differences in their designs that can impact how well or poorly a particular technique works.
The hot start techniques I use have been proven over thousands of hours, across multiple aircraft for each manufacturer. Top induction, top exhaust, bottom induction and exhaust, turbocharged, naturally aspirated, it really doesn't matter. A number of PoA members (and others) have also attempted to hot start a plane with me in it, and after their technique doesn't work, I ask to use mine, which works >99% of the time. I say >99% and not 100% because none of these work 100% of the time, sometimes you get just the right combination of circumstances that the engine doesn't want to start and you have to try something out.
I should start out by mentioning a some things:
1) A lot of times, starting troubles are as much (or more) a weak ignition rather than starting technique. Are your plugs old? Are they Tempest plugs? (if they aren't, buy Tempest) Condition of your ignition harnesses? Magnetos? A good ignition system will help starting, and everything else. Electronic magnetos should provide a better start during cranking and improve hot starts (and cold starts).
2) If your engine is cranking slowly, this will also make hot starts hard, and on Continentals can end up damaging/breaking your starter adapter. Make sure your batteries and battery cables are in good condition. If they are original, replace them. If they're aluminum, replace them with copper.
3) Lycomings and Continentals have different starting techniques, because their fuel injection systems are completely different in design. A hot start technique, in order to work, needs to properly accommodate the fuel injection system that it's working for. I'm not going to go into the design of each fuel injection system.
4) These apply to mechanically fuel injected engines. Not carburetors, not pressure carburetors (such as used on the original 310s), not FADEC or electronic engine control engines - mechanical injected engines. So for example, an IO-540-C4B5, TIO-540-J2BD, TSIO-520-NB, IO-520-E, etc.
Now, my starting techniques.
Lycoming hot start technique:
1) Throttle and prop full, mixture at idle cut-off
2) Turn on fuel pump
3) Push the mixture to full rich for ~8 seconds
4) Pull the mixture back to idle cut-off
5) LEAVE THE FUEL PUMP ON
6) At this point, you should have the fuel pump on, throttle and prop full forward, mixture at idle cut-off
7) Start cranking the engine. When it catches, push the mixture forward (not slowly, but not quickly) and pull the throttle back relatively quickly. With practice, you'll get the timing right.
On my Aztec, I was able to get this such that a hot start would settle right into a 600-900 RPM idle most of the time
Continental hot start technique:
1) Throttle, prop, and mixture all full forward
2) Fuel pump on prime (high pressure/flow) for about 4 seconds (similar to a prime for a cold start)
3) Fuel pump off
4) Start cranking the engine. While cranking, pull the throttle back slowly (slow enough that it's about 5 seconds from full forward to idle). When it catches, you may have to accelerate how quickly you pull the throttle back to prevent it from revving too high. Normally, it catches by 1/4 throttle.
Alternate Continental hot start technique (which I've only had to use a few times - use technique 1 first):
1) Throttle, prop, and mixture all full forward
2) Fuel pump on prime (high pressure/flow) for about 8 seconds (similar to the Lycoming hot start)
3) Fuel pump off
4) Mixture to idle cut-off
5) At this point, you should have fuel pump off, mixture at idle cut-off, throttle and prop full forward
6) Start cranking the engine. When it catches, push the mixture forward and then throttle back, similar to a Lycoming hot start
The primary Lycoming and Continental starts should work for virtually all engines, virtually all of the time.
As I tell everyone who I tell these techniques to: if you have a technique that works for you and you're happy with for your plane/engine combination, keep using it. My techniques are not the only ones that work and they may not be the best on your engines. But, in my experience they do work well and consistently. I put in guidelines for timing, but you'll get the feel of it after a while. As I implied above on some of the things to check if you have hot start issues (or many other issues), general engine/airplane condition are important. No amount of good technique will overcome a starter cable that's broken.
The hot start techniques I use have been proven over thousands of hours, across multiple aircraft for each manufacturer. Top induction, top exhaust, bottom induction and exhaust, turbocharged, naturally aspirated, it really doesn't matter. A number of PoA members (and others) have also attempted to hot start a plane with me in it, and after their technique doesn't work, I ask to use mine, which works >99% of the time. I say >99% and not 100% because none of these work 100% of the time, sometimes you get just the right combination of circumstances that the engine doesn't want to start and you have to try something out.
I should start out by mentioning a some things:
1) A lot of times, starting troubles are as much (or more) a weak ignition rather than starting technique. Are your plugs old? Are they Tempest plugs? (if they aren't, buy Tempest) Condition of your ignition harnesses? Magnetos? A good ignition system will help starting, and everything else. Electronic magnetos should provide a better start during cranking and improve hot starts (and cold starts).
2) If your engine is cranking slowly, this will also make hot starts hard, and on Continentals can end up damaging/breaking your starter adapter. Make sure your batteries and battery cables are in good condition. If they are original, replace them. If they're aluminum, replace them with copper.
3) Lycomings and Continentals have different starting techniques, because their fuel injection systems are completely different in design. A hot start technique, in order to work, needs to properly accommodate the fuel injection system that it's working for. I'm not going to go into the design of each fuel injection system.
4) These apply to mechanically fuel injected engines. Not carburetors, not pressure carburetors (such as used on the original 310s), not FADEC or electronic engine control engines - mechanical injected engines. So for example, an IO-540-C4B5, TIO-540-J2BD, TSIO-520-NB, IO-520-E, etc.
Now, my starting techniques.
Lycoming hot start technique:
1) Throttle and prop full, mixture at idle cut-off
2) Turn on fuel pump
3) Push the mixture to full rich for ~8 seconds
4) Pull the mixture back to idle cut-off
5) LEAVE THE FUEL PUMP ON
6) At this point, you should have the fuel pump on, throttle and prop full forward, mixture at idle cut-off
7) Start cranking the engine. When it catches, push the mixture forward (not slowly, but not quickly) and pull the throttle back relatively quickly. With practice, you'll get the timing right.
On my Aztec, I was able to get this such that a hot start would settle right into a 600-900 RPM idle most of the time
Continental hot start technique:
1) Throttle, prop, and mixture all full forward
2) Fuel pump on prime (high pressure/flow) for about 4 seconds (similar to a prime for a cold start)
3) Fuel pump off
4) Start cranking the engine. While cranking, pull the throttle back slowly (slow enough that it's about 5 seconds from full forward to idle). When it catches, you may have to accelerate how quickly you pull the throttle back to prevent it from revving too high. Normally, it catches by 1/4 throttle.
Alternate Continental hot start technique (which I've only had to use a few times - use technique 1 first):
1) Throttle, prop, and mixture all full forward
2) Fuel pump on prime (high pressure/flow) for about 8 seconds (similar to the Lycoming hot start)
3) Fuel pump off
4) Mixture to idle cut-off
5) At this point, you should have fuel pump off, mixture at idle cut-off, throttle and prop full forward
6) Start cranking the engine. When it catches, push the mixture forward and then throttle back, similar to a Lycoming hot start
The primary Lycoming and Continental starts should work for virtually all engines, virtually all of the time.
As I tell everyone who I tell these techniques to: if you have a technique that works for you and you're happy with for your plane/engine combination, keep using it. My techniques are not the only ones that work and they may not be the best on your engines. But, in my experience they do work well and consistently. I put in guidelines for timing, but you'll get the feel of it after a while. As I implied above on some of the things to check if you have hot start issues (or many other issues), general engine/airplane condition are important. No amount of good technique will overcome a starter cable that's broken.
