I read a thread about hot starts on the IO520 on the 180/185 club website and was wondering if anyone had heard this method before:

Sure-fire, works every time for me hot start procedure for IO520:
Mags off
Mixture, idle cut-off
Throttle, all the way in
Master switch,on
Fuel boost pump, both sides on for 15 seconds. This circulates cold fuel thru the system purging the vapor but does not let fuel into the engine
Now, just do normal start:
Throttle, closed
Mixture, rich
Fuel boost pump, low side on
Throttle, open until 8-10gph on fuel flow, then closed
Starter, engage with mags on
Throttle, open slowly until engine fires

While the method seems to make sense to me because of the fuel return line on the IO520, I had never heard of it before. Anyone else have their own tips on this engine? We've had occasional issues on hot starts on the 185 that we never have with the Lyc. IO540 on the Bush Hawk.

I have never had any real issues on a hot start, I may just have to crank a little longer. Always a concern when on floats, you are by yourself and it is windy.

Steve

A very similar procedure was given to me by a friend shortly after I got my 205. Works every time and I've not had any hot start issues.

Mike-

There are lot of variations for hot starting a Cont IO-520/550. The fuel pump is buried toward the back/bottom of the engine and gets hot... which leads to vapor lock... thus hard to start.

The variation I've used with the most success is to run the fuel pumps for a minute---- 60", prime as described and then start with throttle full in and mixture idle cutoff. Once it starts you have to be quick to swap the throttle to idle and the mixture in.

YMMV,
gunny

My friend that flys out of Southern Seaplanes to the oil rigs uses this method---he does lots of hot starts. Throttle in all the way, pretty sure I remember mixture in, hit the fuel pump for a few seconds until the needle comes up a ways. Hit the starter and start pulling the throttle back until it gets to the "sweet spot" and fires. I might not remember the mixture for sure, but I know the throttle was wide open and being pulled back as the engine cranks.

TCM has a publication called Tips on Engine Care. In there, the procedure for hot starting a Continental engine is described. Their method is slightly different from what you listed in that they do not turn on the boost pump after purging air from the fuel lines and before hitting the starter. The theory is that a little bit of fuel makes it past the spider even with the mixture at cutoff during the circulation step.

I only use this method if my own method doesn't work which is to hit the starter and get the engine going. As soon as it starts (and before it quits) I flip on the High boost pump. Usually it pushes fuel through the vapor lock and the motor keeps running.

I've seen people with injected Lycomings follow their published procedure but it seems like too much fancy knob pushing and pulling to me.

I've always found that the TCM guidance in their POH for the airplane (in the expanded procedures section) works just fine. There are probably an innumerable ways you can get the things to start, but the essential problem you have to get around is freeing the fuel LINES and FI Distributor of vapor (not the electric pump, which is at the bottom of the cowling).

BUT, for totally different reasons than starting the engine, I do have a different start procedure than TCM recommends, in that I add one step to their recommended starting procedure. THis procedure is inserted into the standard TCM procedure as recommended in the POH.

To start the engine, I ALWAYS follow this procedure:

Master: On
Mixture: Full Rich
Throttle: Idle
Fuel Pump: Yellow side: On
Throttle: Advance from Idle to Wide Open
Fuel Pump: Red Side: On
Throttle: Idle
Fuel Pump: Both sides: Off
Starter: Engage
Throttle: Slowly advance till engine start.

During this sequence, you'll note that I engage the yellow side of the electric fuel pump FIRST with the throttle closed, then advance the throttle to wide open. During this process, you should be LISTENING to the electric fuel pump. With the throttle at idle, that electric pump will make a whirring sound as it runs with the yellow side of the switch engaged. Now, as you push the throttle to wide open, you SHOULD hear the pump increase in RPM to a somewhat higher speed.
Then, as you engage the RED side of the fuel pump switch, you should hear the fuel pump run at an even higher rpm.

If you do NOT hear these three speeds of the auxiliary fuel pump, the airplane is NOT airworthy, and should not be flown under any circumstances.

There is a connection between the throttle control and the fuel pump, which switches the fuel pump from a low rpm setting to a medium speed setting as the throttle is opened. This function is there so that, if the engine driven pump were to fail, you could engage the yellow side of the switch, and the electric pump would provide an appropriate volume of fuel to the engine, low rpm if the engine is at idle, thus preventing flooding the engine, and higher, medium rpm and flow for normal cruise flight.

But, with the fuel pump switch yellow side engaged, and you push up full throttle, AND max RPM on the engine (in other words, you ask for max power, as in a go around) the medium side of the pump will not provide sufficient fuel flow to run the engine at 300 hp. That's when you need to engage the RED side of the pump, to achieve max fuel flow, for a balked landing, for example, or climbing out of a canyon.

BUT, if you haven't verified that the YELLOW side of the switch provides differing fuel flows depending on throttle position, and the engine driven pump fails.....you won't be able to maintain cruise power settings, because the engine won't be receiving sufficient fuel to run at that power setting.

Soooo, then, you'd have to engage the RED side of the pump switch, which gives you max fuel flow. Ahhhhh, life is good again.

Except for one minor detail: Those electric pumps run really HOT. Cessna estimates that the electric fuel pump on one of these airplanes will last approximately five to ten minutes at max rpm before it burns up, and stops. At which point, you land.

So, the reason Cessna puts THREE SPEEDS on that fuel pump to to provide proper fuel flows at the three most necessary engine power settings: Cruise power, Idle power, and Max power.

If you don't verify all three speeds on that fuel pump on every start, you won't KNOW for sure that you'll be able to maintain flight if your engine driven pump fails.

Engine driven pumps don't fail often. My only case of this occurred out over Shelikof strait, enroute to Kodiak, at about 1500 feet and ten miles from land........I switched on the yellow side of the fuel pump switch and went on to Kodiak.....no sweat.

Have I ever found one of these airplanes where advancing the throttle didn't increase the speed of the fuel pump with the yellow switch engaged? Yes, Four of them.....

MTV

mtv wrote:I've always found that the TCM guidance in their POH for the airplane (in the expanded procedures section) works just fine. There are probably an innumerable ways you can get the things to start, but the essential problem you have to get around is freeing the fuel LINES and FI Distributor of vapor (not the electric pump, which is at the bottom of the cowling).

BUT, for totally different reasons than starting the engine, I do have a different start procedure than TCM recommends, in that I add one step to their recommended starting procedure. THis procedure is inserted into the standard TCM procedure as recommended in the POH.

To start the engine, I ALWAYS follow this procedure:

Master: On
Mixture: Full Rich
Throttle: Idle
Fuel Pump: Yellow side: On
Throttle: Advance from Idle to Wide Open
Fuel Pump: Red Side: On
Throttle: Idle
Fuel Pump: Both sides: Off
Starter: Engage
Throttle: Slowly advance till engine start.

During this sequence, you'll note that I engage the yellow side of the electric fuel pump FIRST with the throttle closed, then advance the throttle to wide open. During this process, you should be LISTENING to the electric fuel pump. With the throttle at idle, that electric pump will make a whirring sound as it runs with the yellow side of the switch engaged. Now, as you push the throttle to wide open, you SHOULD hear the pump increase in RPM to a somewhat higher speed.
Then, as you engage the RED side of the fuel pump switch, you should hear the fuel pump run at an even higher rpm.

If you do NOT hear these three speeds of the auxiliary fuel pump, the airplane is NOT airworthy, and should not be flown under any circumstances.

There is a connection between the throttle control and the fuel pump, which switches the fuel pump from a low rpm setting to a medium speed setting as the throttle is opened. This function is there so that, if the engine driven pump were to fail, you could engage the yellow side of the switch, and the electric pump would provide an appropriate volume of fuel to the engine, low rpm if the engine is at idle, thus preventing flooding the engine, and higher, medium rpm and flow for normal cruise flight.

But, with the fuel pump switch yellow side engaged, and you push up full throttle, AND max RPM on the engine (in other words, you ask for max power, as in a go around) the medium side of the pump will not provide sufficient fuel flow to run the engine at 300 hp. That's when you need to engage the RED side of the pump, to achieve max fuel flow, for a balked landing, for example, or climbing out of a canyon.

BUT, if you haven't verified that the YELLOW side of the switch provides differing fuel flows depending on throttle position, and the engine driven pump fails.....you won't be able to maintain cruise power settings, because the engine won't be receiving sufficient fuel to run at that power setting.

Soooo, then, you'd have to engage the RED side of the pump switch, which gives you max fuel flow. Ahhhhh, life is good again.

Except for one minor detail: Those electric pumps run really HOT. Cessna estimates that the electric fuel pump on one of these airplanes will last approximately five to ten minutes at max rpm before it burns up, and stops. At which point, you land.

So, the reason Cessna puts THREE SPEEDS on that fuel pump to to provide proper fuel flows at the three most necessary engine power settings: Cruise power, Idle power, and Max power.

If you don't verify all three speeds on that fuel pump on every start, you won't KNOW for sure that you'll be able to maintain flight if your engine driven pump fails.

Engine driven pumps don't fail often. My only case of this occurred out over Shelikof strait, enroute to Kodiak, at about 1500 feet and ten miles from land........I switched on the yellow side of the fuel pump switch and went on to Kodiak.....no sweat.

Have I ever found one of these airplanes where advancing the throttle didn't increase the speed of the fuel pump with the yellow switch engaged? Yes, Four of them.....

MTV

Mike,

Thanks for taking the time to write all of this out. This is EXACTLY why I love this website so much - lots of great input from people who have "been there, done that". I'm definitely going to check this out from now on!

Do you know of any continuing requirements to check the operation of the pump in the manner you described, either through a service bulletin or maintenance manual procedure? Where did you learn this technique, or what led to it for you?

Not all Cessnas are set up with that dual yellow and red switch arrangement. In the 185E, there is only a start position (toggled down and coupled to the starter) and an emergency position (toggled up with low and high speeds tied to throttle position). In other words, 2 speeds not 3, and different switch arrangements.

Squash wrote:Not all Cessnas are set up with that dual yellow and red switch arrangement. In the 185E, there is only a start position (toggled down and coupled to the starter) and an emergency position (toggled up with low and high speeds tied to throttle position). In other words, 2 speeds not 3, and different switch arrangements.

Our '77 A185F with the IO520D has the split-switch arrangement MTV described.

Squash wrote:Not all Cessnas are set up with that dual yellow and red switch arrangement. In the 185E, there is only a start position (toggled down and coupled to the starter) and an emergency position (toggled up with low and high speeds tied to throttle position). In other words, 2 speeds not 3, and different switch arrangements.

Different switch arrangements, but there's still a high and low speed on the pump, mechanically connected to the throttle. That still needs to be checked prior to flight, for the same reasons.

Just different switchology, but basically a similar system.

MTV

CapnMike wrote:Mike,

Thanks for taking the time to write all of this out. This is EXACTLY why I love this website so much - lots of great input from people who have "been there, done that". I'm definitely going to check this out from now on!

Do you know of any continuing requirements to check the operation of the pump in the manner you described, either through a service bulletin or maintenance manual procedure? Where did you learn this technique, or what led to it for you?

Mike,

I learned that procedure from the guy who checked me out in the 185. I always just assumed that everyone did this, till I started doing some training and flight reviews.....

I am not aware of any SB or such requiring this, I've always assumed that mechanics check this at periodic maintenance, but a lot of stuff can happen between those, particularly in Part 91 ops. In any case, it only takes one oops to really ruin your day, and this connection between the pump switch and the throttle is mechanical, and we all know those don't last forever.

As I noted, in my opinion, if you don't have the connection between the throttle and the electric pump, the airplane is not airworthy.

If you read the section in your POH on the fuel system carefully, they describe this connection, though they don't specifically describe how you should check it. In my opinion, Cessna should have added this to their recommended start procedures.

MTV

mtv wrote:If you read the section in your POH on the fuel system carefully, they describe this connection, though they don't specifically describe how you should check it. In my opinion, Cessna should have added this to their recommended start procedures.

MTV

I always have copies of the 185 and the Bush Hawk POH's sitting next to me when I'm reading BCP. Every time people get into technical discussions about different systems, I end up pulling them out and poring over them to see how our airplanes are similar or different, and to ponder the applicability of whatever the particular "wisdom du jour" being discussed might be to our operations. Needless to say, I've learned a lot more about both of our planes doing this!

The OP on the 180/185 club forum had me diving into the books to make sure I fully understood what I was reading. I like the practical application, as well as the anecdotal information you added, and I'm sure this is going to stick with me now. I will be adding this 3-speed fuel pump check to my routine from now on! Thanks again.

Mike,

I failed to mention that this three speed fuel pump check serves two functions during the start: It verifies the pump functions and it primes the engine/clears vapor lock to facilitate the start.

So, it's just an easy thing to add, and quickly becomes habit.

An interesting note was that I flew these airplanes for a couple years, doing this at every start, and everything peachy. Then one day, I was sent to pick up a 185 and ferry it to maintenance. Went through the prep for start, and as I advanced the throttle, the electric pump kept running at low speed.......Holy shit! This stuff is real!

Parked the plane till a mechanic could fix it.

A month later, it happened again, this time in my assigned airplane......

I began doing as you noted.....really reading the POH.

MTV

I've tried it all. Everything I've ever read that anyone has ever posted. Nothing worked 100% of the time, nor quickly. I even hired this guy to try and help:

That didn't work either. of course he was able to get rid of that unsightly wart...and the neighbor's rooster no longer wakes me up...so not a complete loss

But Finally a simple solution that works 100% of the time. Now I can cancel that surgery for adding a third arm so I could use the starter, throttle and mixture all at the same time.

On the trip to Arkansas we stopped for fuel. I told everyone I had a deck of cards so we could entertain ourselves while we waited 30 minutes for the engine to cool down so I could start it. Scot Warren told me he had a way that always worked for him. Of course I didn't believe it would work cause I'd tried everything, but gave it a try anyway.

1. Throttle all the way forward
2. Mixture all the way forward.
3. Boost pump on (low or high or whatever - doesn't matter) until gauge shows about 14. Boost pump off.
4. Crank the engine while slowing closing the throttle.

Engine fires. Hallelujah! Hallelujah! Hallelujah! And the throttle is going the correct way!

Works absolutely every time. Minimal engine cranking. No over-revving on startup. And no three handed manipulation of controls or magic dance with the throttle and mixture. No running the boost pump with mixture out throttle in "to cool the lines" like Continental directs (which did nothing to help btw).

Thank you Scot!

I believe you described what I did in my post before. My friend that flys out of Southern Seaplanes uses that method also. My first trip with him we flew to the very end of the Mississippi to an oil rig on the west side. After a few minutes we hopped in (he let me get in the left seat even) and flew about two minutes to a rig on the east side. Then several others rigs making one hot start after another. Never failed to start easily.

one thing that really seems to matter on the hot start procedure is, how long it was shut down.
< 10-15 min, almost anything will work. go in and have lunch on a hot day? well, some times I thought I was gonna see somebodies starter run out the bottom of the cowling
the sure fire method I learned was, the purge like everyone else uses. but then, mixture lean, throttle open about 1", low side fuel pump on, engage starter, start screwing in the mixture till it fires. wa'la.
seems like sometimes its more art than science, maybe voodoo.
then also, some times variation in technique is required because the whole F.I system is out of spec

OK, there seems to be a little confusion on the speeds of the electric fuel pump.

There are only 2 speeds on the Cessna's, not 3!

Cessna's have a 2 sided switch "Low and High". Which works as follows: If the low side is switched on you will only get low boost! If both are switched on you should get Low if the throttle is pulled back and High starting at somewhere around 1/2 throttle.

There are a couple of adjustable resistors in the circuit as well as a micro switch that makes the fuel pump run at 2 different speeds.

The reason for the low and high is as follows:

If the engine driven pump takes a dump while flying. The throttle is pushed in so you need high boost in order to have enough fuel pressure to run the engine at a higher power setting.

If the switch is on the high position without the micro switch circuit and resistors if you pulled back the throttle (without a major mixture knob adjustment) the fuel pressure would be too high and possibly kill the engine.

So as you pull the throttle back the micro switch will switch you to "low" even when the high side is switched on.

That way if the resistors are set up right the engine shouldn't quit on you example: when you are coming in for a landing with an inop engine driven pump.

The low side switch is supposed to be for starting and low power settings.

On the early fuel injected models the low side didn't do anything if you switched it on until you are in the start position on the key switch, then it will only pump low.

On the newer models low pump will come on without being in the start position.

I'm not sure when the switching changed changed I think late 60's maybe.

(I always use the high side with full throttle for prime myself)

I have found that many planes are not set up correctly!

A quick ground check is with the engine off and full throttle and mixture, when you hit the high side of the switch your needle should get above the green fuel flow arc.

If it doesn't then you won't have full power if your engine driven pump quits!