28v GPU Question

[csarles]

I live in Michigan and try as I may, not every start attempt results in an engine start during the winter. Often, I find that I run out of battery power before the beast will fire up. Does anyone knows if using the GPU port on the side of the Bravo will provide cranking power and recharge the batteries?

Curt

[Piloto]

It will do both. Best approach to starting is to connect the GPU 15 minutes before cranking and then crank. No need to turn master on to charge the battery. Try starting without the GPU connected otherwise you will need someone to disconnect the GPU after start.

José

[csarles]

Thanks. 

[LANCECASPER]

I used to live in Minnesota and North Dakota before moving to Texas.
Pre-heating the engine makes the start a lot easier and is a lot better on the engine since the oil flows right away. Many airplanes up North have Tanis or Reiff engine heaters on them plugged into a thermostatically controlled power outlet. When it gets below a certain temp the pre-heater comes on. http://www.sportys.com/pilotshop/thermo-cube-for-heater-35-degree-f-set.html 

Or they have a device called a Switchbox which has a sim card and you call the number a couple hours before you go to the airport and it switches on the heater and makes life easier. http://switchboxcontrol.com/the-switch-box/

Keeping a Battery Minder trickle charging the batteries helps too.

For Gill: http://www.batteryminders.com/24-volt-aircraft-battery-charger-24041-AA-S2

For Concorde: http://www.batteryminders.com/24-volt-aircraft-battery-charger-24041-AA-S5

Charge both batteries at the same time: http://www.batteryminders.com/batteryminder-accessory-model-210-rt-smartechnology-2-multiple-battery-connector-w-ring-terminal-connector/

[Awful_Charlie]

Note that the external power socket only charges battery #1 (the one on the left) - if you want to charge #2 then you either need to plumb in some leads or remove one of the side panels.

However, if you're not managing to get a start out of two batteries even in the cold, I think there is something else that needs attention - mags, starter, leads, relays, possibly even your technique?

[csarles]

How long do you run the aux pump before starting?  Do you follow the book for each temp?

I can do hot engine starts all day long, it's the cold engine ones that bugger me up. I have taken to leaving the Tannis plugged in and a blanket over the cowl, that seems to help. 

Any advice on cold engine starts is appreciated. (Side note, may need a couple of batteries...)

[carqwik]

Are you using the priming time graph in the POH before starting?  In cold wx, it's pretty long...like 20+ seconds as I recall.  Since my POH is in the plane, I can't quote specifics but the graph shows ever increasing prime (boost pump on) as the temps drop.  Of course, anything below 40 F requires pre-heat...

[FoxMike]

This is kind of a longshot but it happened to me.  My Bravo had starting problems at temperature extremes.  Finally traced the problem to the factory wiring the left mag to the right mag on the switch.  This does not allow for retard during starting.  Only one mag has retard (left one if I remember correctly).  You or your mechanic can trace the the wiring and make it right without buying any parts.  An ohm meter is the only tool you need and a wiring diagram.  Good Luck!

[jlunseth]

I have a 231 so I am not sure my trick will work on a Bravo, but am guessing it does.  The problem I had with cold weather starts was that the engine would fire, but would quit right away.  Several attempts later, with more "short hitting," and the battery would be gone.  What I discovered sometimes worked was to push the High Boost button.  There is a way to push my High Boost that makes it an "instant on, instant off" switch.  It is behind a safety guard and I do not move the safety guard over.  Rather, I hit just the top of the switch until the safety guard stops the switch from going further.  This way, it turns the pump on, but the switch never locks in the full on position, so the moment I release pressure the boost pump is off.  At any rate, what this does is provide fuel flow to the cylinder so that once it fires, it just keeps going.  Eventually the mechanical pump kicks in and the engine does not need the help.  This cures all kinds of starting problems for me in the TSIO-360-LB.  It is unfortunately not a complete fix at super cold temps.  When it gets down around zero F, I better have plugged the engine in beforehand.  The fix I get into, is that I will call the FBO, ask them to plug the plane in prior to a trip, and about half the time the line kid forgets, or can't figure out where the plug is, or something like that.  Last time they had the wrong aircraft number.  So there I am, needing to make a cold weather start if I want to make the trip.  If it is not brutally cold the High Boost will fix it.

The other issue, though, if you have to make a cold weather start without having let the engine and engine compartment warm up first, is that you have to give those things a chance to get good and warm before you go anywhere.  I can't begin to list the weird things that can happen if you don't, the most "interesting" one I had was the air/oil separator freezing up and blocking any breather flow out of the engine.  There have been others.  So let the whole compartment get nice and toasty before you take off.  If you don't, low altitude dense air will supercool everything really fast.

[carusoam]

Things to consider...

1) a cold start is similar to a normal start with one difference.  The amount of fuel required to get the same priming effect.  The evaporated portion of the shot of prime is important.  The evaporated portion changes with temperature.

2) The usual POH gives the cut-off of <40°F as the temperature to use cold start procedures.

3) The POH will give a range of seconds on the high boost for cold temps.  Something like 3 - 6 seconds. If three works for normal starts then the other end of the range is better for coldest starts.

4) The Whole cold start thing falls apart at 20°F and below.  This is approximately the temperature where 100LL fails to evaporate.  No evaporation, no ignition.  Between 20 and 25° evaporation rate is slow and appears to use the most prime to get the same effect.

5) Getting it started with the right priming is one part, keeping it running is the next challenge. The low boost is usually used for the first few minutes on a cold day.

6) Keep account of the excess fuel used in cold weather priming.  It has to go somewhere.  Make sure the drain is working.  Know that the tire is getting wet.  Have plan B in mind when the excess gets ignited.

 

 

My IO550 cold start procedure includes multiple steps...

1) Throttle and mixture full in.  (Priming with the throttle or mixture out doesn't work the same on my engine!)

2) High boost on for three to six seconds (timed after FF is indicated).

3) shut off the high boost.  Count some seconds 15 to 30, evaporation takes more time when its cold...

4) reset the throttle for start.

5) low boost on (simultaneously with step 6)

6) start.  (Count the blades as they go by)

- two or three is really good.

- five to ten, could be better.

- 15 to dead battery, adjust amount of prime, timing or other things, could be a lot better.

7) adjust throttle back to 1000rpm

8) low boost off. (If it stumbles, low boost on)

9) as the engine heats up, lean the mixture.

 

Now I remember what not having a primer pump on my M20C was like.  There is not an elegant way to add just a little more fuel while the engine stumbles and dies.  The second start is not the same cold start or a normal start...

Looking forward to a reliable and affordable electronic engine computer.

How's my thought process today, what did I miss?  Feel free to point out any errors...

Best regards,

-a-

[carusoam]

Thoughts on the usability of the Aux power port....

1) it has safety limits wired into it.  A solenoid switch actively keeps things from being connected backwards.

2) modern electronic chargers/boosters try to sense the battery on the other side, also to keep things from being connected backwards.  With the solenoid open, the charger doesn't sense the battery and does not send any current.

3) A second external battery can be used to open the solenoid.  This adds to the challenge of getting a proper charge to include the extra load of the extra battery and closed solenoid.

4) It is only connected to the #1 battery.

5) It works really well with a fully charged external battery, or bank of batteries from a cart.

6) It may help to know how many electric memory devices you have on board.  These seem to drain a battery excessively.

7) It may help to know who built your battery.  One manufacturer is better than the other.

That's all I got.  This is the experience of a PP living in NJ with years of outdoor storage.

Best regards,

-a-

[csarles]

Thanks for all the advice. I have owned the bravo now for about 6 years and agree that the best way to get the engine to fire is to keep it warm and in my hangar.

What started this was I landed and was waiting in 20f weather for my mom to show up so I could fly her to SC to see my sister. It sat outside for about an hour and by the time I went to start it, the oil had cooled to 60c. I knew then that I had one opportunity to get it to fire. I primed it as recommended in the POH (10-15 seconds if I recall correctly), turned off the primer (94 bravo, I only have on or off) waited about 10 seconds and cranked. It fired once and died and this is what generally happens if it's cold. Subsequent attempts only cause the batteries to die and fuel to drip out the bottom of the cowl. This last time I pulled the cowl and removed the mags, the top were dry but the bottom were soaked. I cleaned and dried them. By this time the plane was warmed up in the hanger so it fired up nicely. 

I look forward to trying the method nicely outlined above (thank you -a-) the next time it's cold. 

The original question about charging the batteries is because I like to be self sufficient instead of relying on a small municipal airport fbo to recharge the batteries as they aren't open evenings or weekends. 

[Awful_Charlie]

I have no problems with cold starts, it's the hot ones that get me.  For cold, prime with full mixture and throttle (I don't use the panel pump switch) for the book time, start counting after the pump drops in note as it comes under load. Turn the pump off by pulling the throttle all the way to closed, then two or three twists in. Beacon light on, holler out the window, have a looksie around, twist and push the key and it will start after a few blades. If it doesn't keep going, then not enough prime or not enough throttle, so do the same again only adding a couple of seconds of prime and/or an extras twist. Works for me ok down to about -10C, I haven't got much experience of many starts colder than that

[Mark Nit]

Hey guys,

I may the winner of the Bravo cold-start contest.  I'm located in Winnipeg, Canada and I travel up close to the Arctic in the cold -30' Canadian winters in my '91 TLS.  And I don't use a heated hangar. I have a few tricks for the cold weather that I've learned after freezing two sets of Gill batteries. First, I keep a small 120 volt heater set on low in the battery compartment during the coldest days. A thick blanket over the rear helps to cut down on the heat loss. As well, I've installed a 120 volt glue-on oil panheater (aka block heater) and I use a thick engine cover. I turn on the heater the night before a flight. Do not leave the heater on much longer as this leads to excessive moisture build-up and corrosion in the engine. Once I prep and preflight, I unhook and uncover everything and fire her up before the oil has a chance to cool down.  Usually 6 seconds of boost is enough to get her going. If the batteries do run low, be sure to charge them both as they freeze (and die) a lot quicker when they're discharged. And thank goodness for the great cabin heater and defrost. It's surprising good for a Texas-built plane !!!

[L. Trotter]

I was told by the late Al Pietsch (Minot, ND) that the original Mooney heater (from Tx) were not very effective back in the day. Al worked with Mooney to redesign the heater to keep the northern tier boys warm during the ridiculously cold ND winters. I suspect Warren or Kent Pietsch could fill in all the details. Just a little Mooney trivia......

[M20S Driver]

On 11/28/2015 at 2:31 PM, carusoam said:

Things to consider...

1) a cold start is similar to a normal start with one difference.  The amount of fuel required to get the same priming effect.  The evaporated portion of the shot of prime is important.  The evaporated portion changes with temperature.

2) The usual POH gives the cut-off of <40°F as the temperature to use cold start procedures.

3) The POH will give a range of seconds on the high boost for cold temps.  Something like 3 - 6 seconds. If three works for normal starts then the other end of the range is better for coldest starts.

4) The Whole cold start thing falls apart at 20°F and below.  This is approximately the temperature where 100LL fails to evaporate.  No evaporation, no ignition.  Between 20 and 25° evaporation rate is slow and appears to use the most prime to get the same effect.

5) Getting it started with the right priming is one part, keeping it running is the next challenge. The low boost is usually used for the first few minutes on a cold day.

6) Keep account of the excess fuel used in cold weather priming.  It has to go somewhere.  Make sure the drain is working.  Know that the tire is getting wet.  Have plan B in mind when the excess gets ignited.

 

 

My IO550 cold start procedure includes multiple steps...

1) Throttle and mixture full in.  (Priming with the throttle or mixture out doesn't work the same on my engine!)

2) High boost on for three to six seconds (timed after FF is indicated).

3) shut off the high boost.  Count some seconds 15 to 30, evaporation takes more time when its cold...

4) reset the throttle for start.

5) low boost on (simultaneously with step 6)

6) start.  (Count the blades as they go by)

- two or three is really good.

- five to ten, could be better.

- 15 to dead battery, adjust amount of prime, timing or other things, could be a lot better.

7) adjust throttle back to 1000rpm

8) low boost off. (If it stumbles, low boost on)

9) as the engine heats up, lean the mixture.

 

Now I remember what not having a primer pump on my M20C was like.  There is not an elegant way to add just a little more fuel while the engine stumbles and dies.  The second start is not the same cold start or a normal start...

Looking forward to a reliable and affordable electronic engine computer.

How's my thought process today, what did I miss?  Feel free to point out any errors...

Best regards,

-a-

This advice wins the "2016 best procedure award" for M20S Driver on Mooneyspace...

Today, it only took 3 blades to start at 34 deg f.

[Tony Armour]

Just a note to the 231and O folks. Bravos only have one electric fuel pump setting, no high/low. Maybe a Lyc vs Continue thing. 

[Tony Armour]

On November 21, 2015 at 3:18 PM, csarles said:

I live in Michigan and try as I may, not every start attempt results in an engine start during the winter. Often, I find that I run out of battery power before the beast will fire up. Does anyone knows if using the GPU port on the side of the Bravo will provide cranking power and recharge the batteries?

Curt

I have a GPU but it's only for powering avionics. Plugs in the side port. Not sure that a "GPU" is what you need to jump or maybe not even charge (much) 

What ever you look at read the instructions first so you know going in what the manufacturer recommends.

[carusoam]

Tony,

There is a few pieces of weirdness that come from Continental that get hidden in the POH...

The plumbing for the fuel lines are specific to the engine...   the return line back to the selector valve is unique to the engine.  The O's return line gets selected with the tank selection.  Other Moonies always return to the same tank.

the fuel pump looks like there are two different fuel pumps... a simple hi, lo, off would be more self explained.  Wondering what happens if both switches are turned on at the same time...? The hi switch is dangerous enough that it gets a guard over it...  So a three-way switch is too much of a simplification...

When you prime the Bravo, does the throttle need to be all the way in with the mixture control?

Things that come to mind...

Best regards,

-a-

[PaulM]

Yes, there is a Lyc, Cont difference...  return piping and 2 stage pumps.  

I haven't had a problem starting my Bravo... but if you pre-heat the engine, remember that the timing/temps are for the engine.. which is now the CHT/Oil temp not the OAT.. 

On the bravo the throttle should be at the "start setting-1/4in. ",  which I always leave at 1100RPM when we shutdown" (as per Dave @ All American)

prime for OIL/CHT... wait a few seconds to vaporize.. then crank... 

I have found that if the mag timing is off (left mag is the starter mag) that it is harder to start... It is always perfect out of Annual, and then over the year can become a bit harder to start and needs more throttle. 

[Tony Armour]

On December 20, 2016 at 0:32 PM, carusoam said:

Tony,

There is a few pieces of weirdness that come from Continental that get hidden in the POH...

The plumbing for the fuel lines are specific to the engine...   the return line back to the selector valve is unique to the engine.  The O's return line gets selected with the tank selection.  Other Moonies always return to the same tank.

the fuel pump looks like there are two different fuel pumps... a simple hi, lo, off would be more self explained.  Wondering what happens if both switches are turned on at the same time...? The hi switch is dangerous enough that it gets a guard over it...  So a thread-way switch is too much of a simplification...

When you prime the Bravo, does the throttle need to be all the way in with the mixture control?

Things that come to mind...

Best regards,

-a-

I prime with the throttle in. Many of us don't turn the pump switch on because there is a micro switch on the throttle cable that will turn it on when full throttle.

So, full rich, throttle in until primed then throttle back. This confirms that the micro switch is working. Still turn the pump switch on for take-off and landing. I assume the micro switch is there in case someone forgot.

[carusoam]

Interesting...

The IO550 also gets electric fuel pump support when at full throttle. (While running, according to the POH)   During the priming exercise, The FF reading is typical of the Lo or Hi Boost depending on which switch has been selected.  It is quite audible as well to which mode it is running in. 

Best regards,

-a-