B – Engine Ops


Engine Ops in the ASG32 Motor Glider

By Peter Kelly


Before reading this web page, review both:

This page will help you to become familiar with this Motor Glider – the ASG32Mi.  I have several years of experience flying a predecessor – the ASH-26E, as well several years operating another motorglider – the DG-800B.  Motor gliders are certainly versatile machines, but first and foremost, they are fun gliders to fly.  After you become comfortable with the 32 as a glider you may then learn about operating with the engine.


Attitude (about having a motor)

The most valuable aspect of having a motor is that you can get into the air without a tow plane, but this is not a factor at our gliderport here at Williams Soaring Center (WSC).    The second most valuable aspect is that a motor will allow you to venture forward into areas of unknown lift.   If you are then unable to continue a soaring flight due to a lack of lift, you have the option of either landing at a remote airport, or, you may restart the engine and fly back to the lift that may take you home again.  It is critical that you accept that the function of the engine is to avoid landing at a remote airport.  The function is NOT to save you from a landout in an unlandable area!  There are two well written resources that will help you to understand this concept:

  • The Guide and
  • The Schleicher Manual.

– The Guide
The attitudes you develop regards to operation of the motor are extremely critical to the safe operation of a motorglider.   You may have misconceptions about gliders with motors aboard.  There are many pitfalls that you must avoid.  Thankfully, Eric Greenwell has published an excellent manual which he simply refers to as “The Guide”.  I direct you to Chapter 12 and the first two sub sections of that chapter:

12.1 Are you safer with a motor? and

12.2 The culture of the “Low Save”.

This is a must read publication, and I dare say, is equally as important as knowing the ASG-32 operating manual itself.  Visit the download page that Eric has created: https://sites.google.com/site/motorgliders/publications/download-the-guide-1   (look for the tiny arrow in lower right corner of that page  – that is the download button!).


 – The Schleicher Manual
Over the past 15 years that I have been reading the Schleicher Factory Manual  I have noticed they have refined the wording, but the message has always been the same.  The following is an extract from page 4.17 of the Schleicher Factory Flight Manual for the ASG32Mi :

……………………  The power plant of a powered sailplane must not be regarded as a life insurance, for instance when crossing unlandable areas. One should always be prepared for the possibility that the power plant will fail to deliver the hoped-for propulsion. This may not necessarily be due to a technical shortcoming, but might be caused by nervous tension of the pilot (mistakes in carrying out starting procedure). The engine and its reliability should be regarded in the same light as that of a sailplane pilot not always finding a thermal when it is most urgently needed. The engines of powered sailplanes are not subject to quite such stringent production and test regulations as normal aviation engines, and therefore cannot be expected to be quite as reliable.

I cannot overemphasize the importance of the above words. But for casting shame and embarrassment on others, I would (and could) mention names of pilots you may know, including places, and dates that are examples of reliable engines failing to start, several of which destroyed the motor glider.  Don’t be one of the statistics.  Before you perform the Inflight Engine Start Checklist you must identify the place you are going to land, and of course, you need to be within adjusted/ adequate glide distance of that field (assuming the propeller is extended but not operating).  Personally, I have had the engine fail to start inflight on no less than three occasions, and on each occasion, I landed without incident – and on two of those instances the engine was extended.  Granted that was over a period of 12 years, while accumulating over 1,000 hours of flying time on those two motor gliders, but it could happen tomorrow just as well.

Attitude Summary – Let’s not be afraid of the engine.  It is an asset.  It’s extremely valuable.  The engine in this  ship is the state of the art.  Use it when ever you need it – but be disciplined enough to adhere to the cautions and procedures.



  • Fuel: Unless the engine has been disabled, always preflight the engine as if you are going to use it.  Having fuel is basic, but how much?  In my ships I always insured that I had a full tank of fuel before each flight.  Besides, condensation of water vapor within the tank is less likely with a full tank.
  • Oil: The oil level is critical.  Do not overfill the oil.  Leave between a quarter to a half inch of space in the tank – above the oil.  This prevents spillage and run off from the oil tank overflow into the engine compartment and  thus minimizes possible subsequent fire dangers.  However, do not have much more than a half inch of space above the oil. Oil is needed for the engine bearings and for internal cooling.   This is not a two stroke engine.  Oil and Gas do not mix, but the oil is consumed.  If the engine is operating properly, one full tank of oil will only be consumed if you were to consume two full tanks of fuel, so there is plenty of oil for a single flight, as long as you begin with a reasonably full oil supply.
  • Prop and Belt: Inspect it all carefully looking for the correct belt tension.  Check the tension of the belt, below the sprocket – look for about a 30 degree bend.
  • Overall inspection:  Check safety wire on engine retaining bolt, just aft of the oil tank.  Examine entire engine bay, prop brake, door bungees, door seals and hinges, etc.  Look for signs of fluids or leaks, etc..


Engine Starting
Before I share my personal techniques, let’s look at a few parts of the operating manual.  This is a portion of paragraph 4.5 (but you do you really do need to read the entire flight manual.  Don’t rely on my extracts!)


The flight manual was not written in English.  It was written in German and then translated.  Those you that speak more than one one language understand the subtleties revealed in translated documents.

The above pages contain paragraph 4.5.1 operation of the Power-Plant and Self-Launch.  However this paragraph also addresses “…start in flight” as well as …”Stopping engine and retracting propeller”.

I will add some notes in my “Engine Start” paragraph below.  A few comments that may prove helpful to the above noted pages:

  • Fuel valve: OPEN?  –  Look at the valve and verify that it is open.
  • Power plant main switch: On  –  It is more of a circuit breaker than it is a switch, and it must be pushed in to turned on.
  • ILEC (mentioned twice in the checklist)  is not a navigation computer.  ILEC is an alternate name for the ECU – Engine Control Unit.
  • A question mark ending each step is just a different format than many of us are familiar with, when it comes to a listing of procedures.
  • On the right side above (Cold and warm start in flight) , the inflight start – “the red ECU-LED – off or permanent on?”  This indicates it may sometimes be on.

You can see the need to read the flight manual in order to understand these checklists. To satisfy some of your curiosity let me post a part of the text I found on page 4.19 of the manual:

…….The red ECU-LED normally remains off when the engine is running. If it is permanently on as long as the engine is running, and a message appears in the LC-display, an error has occurred in part of the engine control unit. This has to be repaired prior to the next take-off. If the ECU-LED is permanently on during flight and the engine performs normally, the flight …..

More info from the manual:
From paragraph 2.5 (color added for affect)….


A extract from paragraph 4.5 of the manual:

eng-revsThis is a fixed pitch prop.  If throttle is held constant and you lower the nose to allow the airspeed to increase, then the RPMs will increase. You discover that if you want to fly a constant airspeed, then you need to control the RPM so they remain below your target RPM while you adjust the pitch and get the airspeed stabilized, and THEN, you adjust the throttle to achieve your desired RPMs.  Definitely respect all RPM limits. Not doing so will destroy the engine.

Engine Start

You might be inclined to shorten the Engine Start Checklist by combining certain steps, but since you are renting and are not the owner, you are requested by Rex to “do it by the book”.  Regardless of whether you are on the ground or in the air, you still need to perform these six steps:

  1. Fuel – on
  2. Power – on (ILEC lights)
  3. Prop – extend (green light)
  4. Prop – unlock
  5. Ignition – on
  6. Starter – push

There are variations to these six steps as you can see as you review the above quoted pages of 4.15 and 4.16.

  • After Ignition – On, “Fuel pump 2” is an item that is added to the checklist when starting on the ground. Check that it is off (unless you are about to do a self-launch, in which case it should be on)
  • Throttle position is added just before “Starter – push”.  Throttle is always at idle, except for start on the ground when “engine is cold and warm start on the ground (not too cold)”

Lots of info on those two pages: 4,000 RPM is best for warm up on the ground,  40 degrees coolant is needed for self-launch, Ignition check is done at 6200 RPM, max drop allowed is 300 RPM (be sure prop blast area is clear).

Known the system and have a set sequence for starting. I feel it is safe to say that if you have a mental picture of those six steps you will have the essence of engine start clearly fixed in your mind.

Always run the engine start sequence in the same manner.  Know which cockpit has engine control before you begin.

For an inflight start, here is a sample dialogue you might use in flight, if you want to engage your passenger and make full use of your resources:

“I am going to start the engine.  I have set the flaps to 4,  and the speed is 55 kts.  You take the controls and fly straight ahead, maintaining this speed”.

You should expect the passenger to say: “I have the controls”

Then, do the engine start checklist and within 30 seconds  say:  “Maintain 55 kts as the engine warms up”.

Then, after the engine is warmed up, you might say: “Climb and maintain 55 kts as I advance the power”.



If you do perform a self-launch, it is helpful if you have procedures well established.

  • All pre-takeoff checklists complete prior to engine start
  • Fuel pump #2 on
  • Engine warmed (40 degrees coolant min)
  • Flaps set at Flaps 5 prior to releasing brakes
  • Spoilers closed and locked before throttle is advanced
  • Hand on throttle during takeoff roll, 7100 Min and 7750 Max RPM limits observed
  • Initial climb at 49 kts

After takeoff climb

  • At approximately 500 ft
  • Speed 55 kts and set Flaps 4
  • Begin reducing throttle, 7100 RPM before 1,000 ft
  • Gear up
  • Fuel pump #2 – Off

As you climb the engine air temp will climb quickly, especially on warm days. You should NEVER allow the cooling air temp to exceed 120 degrees.  Take action once the climb is established and avoid exceeding 115 degrees. In order to avoid exceeding 115 degrees, simply retard the throttle,while increasing the airspeed to maintain an RPM of 7100.   7100 RPM is the limit for continuous operation, so respect that by adjusting throttle and airspeed.  Increase airspeed above 55 kts, as necessary, while adjusting the throttle to maintain an RPM of about 7100 ( as the max).  The rpm will naturally increase as the airspeed is increased, thus it is a coordinated maneuver.

Running the engine too hot will destroy the engine.  The lubrication of the moving parts will not occur if the internal surfaces are too hot or if the oil itself becomes too hot.  Without proper lubrication at all times, engine life is decreased significantly.  After shutdown the internal surfaces must be cool enough so that the oil does not evaporate from the metal surfaces.  Thus the engine must be cooled before shutdown.  The internal engine seals (somewhat similar to rings on a four stroke engine) are metal. If the oil evaporates off of the metal, the engine could seize, and, at a later date, rust will form if no oil was left on the seals due to shutdown at a high temp.

Understandably, you may ask – where does  “procedure” of increasing speed to to 55 kts, come from?   My reply is – see page 4.24  The following is an extract from that page:

…….If the internal cooling air temperature is over 120 °C (248 °F), then the climb should be continued at a lower power setting or flown in …

Note that is says   …climb should be continued at a lower power setting…   it does not say at a “lower RPM”.  Let’s agree that you are not going to allow the cooling air temp to get as high as 120 degrees in the first place.

If you observe that the temp is approaching 115 degrees, take action well before it goes any higher.  Lower the nose, reduce throttle, and fly at 55 kts (or even more if needed) with an RPM of 7100.

Here is a more complete extract from page 4.24 of the flight manual….

If the internal cooling air temperature is over 120 °C (248 °F), then the
climb should be continued at a lower power setting or flown in level flight
with around 6000 rpm until the internal cooling air temperature has
dropped significantly (about 5°C, 9°F) before switching off the ignition.
Has the internal cooling air temperature dropped significantly or 115°C
(239°F) was only slightly exceeded during the climb, a cooling run has
to be performed for 1 – 2 minutes at circling speed and 4000 – 5000 rpm
before switching off the ignition. It is advised to perform this cooling run
during centering a thermal. In this setting the engine behaves nearly drag
neutral. It also makes sense from a safety perspective because if the
current thermal is not usable, unnecessary engine stopping and restarting
is avoided. Thus, the pilot’s workload is reduced and this time is
used for cooling the hot inner engine surfaces. The oil film will not evaporate
and stays as lubrication and protection against corrosion of the
engine surfaces.


Engine Shutdown

Assuming you did not exceed 120 internal air temp during the takeoff and climb, and it is now time to shut down the engine and commence with soaring flight, you will undoubtedly always need to do a “cooling run”  here at WSC.  If you ran the engine engine for longer than 5 minutes you probably hit at least 115 on the Internal Air Temp.    Here at WSC you always do a cooling run.



  • Cool it
  • Speed 49 to 59 kts
  • RPM – Stabilized at Idle
  • Ignition – Off
  • Fly the glider – you are probably in a thermal
  • Prop Stop – On (ONLY after rotation stops)
  • Retract Prop – (hold to the beep)  Monitor water temp of a decrease of at least 2 degrees C
  • Retract/Stow the mast – (after pulsing beeps, indicating the temp has dropped 2 deg.)
  • ILEC – Off

Note: With engine switched off (Ignition switch down) and ship stabilized at speed of less than 55 kts, the prop will not windmill, but will rotate very slowly.  Observe that the prop is stopped, but NOT in the vertical position before you push the prop stop lever down.  If prop is slightly past vertical, the prop stop may not engage. After the prop rotates to vertical (against the stop), you may retract the prop.

Engine Ignition switched off:ignition off

Photo below: See the Prop Stop Lever ready to be pushed down.
Take a note of this photo-
Just like every other aircraft I have ever flown the throttle has a round knob at the end of the handle – that is the LEFT ONE!
Note that the lever on the right side is the Prop Stop lever and it has a wide handle on it.
I can even imagine it is in the shape of thumb, similar to the Prop Stop itself that holds the prop from windmilling.


See the prop resting against the Prop Stop, holding the prop from rotating.


Evidence that the prop stop handle was down while the prop was rotating:
using-it to stop-rotationBlack mark on the prop but no real damage.



If the engine fails to start on the first attempt, then the first thing to do is evaluate your situation.  If you are airborne consider your altitude and distance to the nearest landing pattern.  Review your plan B and confirm it is viable.

If the engine failed to start and you have the time to try again, take it from the top.  If it does not start on the second try, I strongly recommend you save all of your trouble shooting and review of possible systems malfunctions until after you land.  When in flight, you have zero visibility of the engine area and you just don’t know what’s going on back there.  After you are on the ground, with the canopy open you are more apt to detect fuel leaks, smoke and fire.  There have been fuel leaks, and there have been fires.  Some fires have been a result of accumulated oil and not fuel, but fire is fire.  Don’t trouble shoot inflight.

If you are flying solo, or not having the other pilot fly the ship while you start the engine, it’s important to stabilize the ship before you start. Flaps set, trim set, airspeed steady at 49 kts.  Scan for traffic before you put your head down.  While you wait those 10 or more seconds for the prop to extend, once again, check airspeed and scan for traffic.  Trim will be changing as the prop comes up and will change again as the engine starts. Since engine start is swift once the prop is up, recheck that you are holding 49 kts, wait until you have the rpm stabilized at warm up RPM and then consider re-trimming.

If you thought the prop was up but starter did not turn the engine – maybe the prop isn’t fully extended (no green light).  The prop needs to be up and locked before the starter will turn the prop. There is a prop up safety switch.




– OFF?  this means  – No red lights.  you should not launch with any red lights on the ECU.
– #2 Fuel Pump should be on for takeoff but turned off when the gear is retracted.

remains off rather than on. If you had used pump #2, then what do you consider a safe altitude?  Next paragraph below (talking about going from Flaps 6 to Flaps 5 says that 500 ft is a safe altitude.

– Power reduction: After 3 minutes? I consider 3 to be max, so I reduce to 7100 RPM before 3 minutes.  Certainly no later than 1,000 ft up.

When pushing up the throttle, do it slowly so as not to have an over speed. Also, it prevents FOD (Foreign Object Damage).  I was getting chips in my props (both DG800 and the 26E)  from small pebbles being picked up and pulled into the prop.









Never move the transfer switch when the engine is running, because doing so will shut down the engine.



mg-stopping-eng-1A “cooling run” will nearly always be required.  The reason?  because if you exceed 115 air temp in the climb, then you need to cool it.




Refueling, Oil Servicing
The Info in this section is really an orientation, not a “how-to”.  Rex will provide you with hands on instruction, if he wants you to be involved in refueling his Aircraft.

  • Plug the hose into the refueling inlet, turn on engine power, see that the refueling switch is on (down position).
  • Refueling should stop automatically. Overflow is on the lower side of the fuselage below the left wing root.  You should not see fuel exiting from that port.
  • Oil filling should only be accomplished when a rag available in hand for instant mop up of any spilled oil.  Do not over fill.  Use your pinky to measure, and stop before the oil level is within 3/4 of an inch from the top of the reservoir.  Clean up any spillage and re-secure the oil filler cap.








Common footer for all ASG-32Mi Pages

Caveat: This page is not intended to be instructional in nature.  Some of my info and techniques may not be correct and may even be in conflict with proper procedure, so due diligence is required by you.  FAR’s take precedence, as does the Schleicher Flight Manual.

Why motor gliders are scary, aka  (not True Confessions, but it is a Real life Story)

Lessons Learned/ Relearned (again)!

I’ve been lucky, more than once while operating a motorglider.  But we all know you can’t always count on being lucky.  If  you need the engine to start to prevent an unplanned poorly thought-out, off field landing, you better have luck on your side.  If the engine fails to start, you are probably going to damage the ship, and maybe even end up in the hospital.  It may seem unbelievable that an experienced pilot would ever put themselves in that sort of a position.

I have lots of experience, and yet I recently (in 2017) ended up  in that exact position. Even though I get a sick feeling in my stomach just thinking about it, I believe a thorough evaluation of the situation is a constructive approach.  It’s so much better to review all of the facts surrounding such a situation.  If an accident had occurred, this same evaluation would be made, but probably not as objectively.  By stating the facts, and evaluating the existing parameters, I feel I can help to prevent myself from doing this again, and maybe you, as a less experienced motor glider pilot, will see how easy it is to get into this kind of a situation. It’s very easy to say …. I would never do that.  or … That couldn’t happen to me, etc… But the fact is, it really could happen to you.

I had started the engine in flight probably 15 times during the preceding three months, and seven times just within the past two weeks.  I was comfortable with the procedures.  Maybe a bit too overconfident in my abilities, and way too confident in the mechanical operation of the motor and associated systems.  On this particular flight I had already started the engine twice during the preceding hour. The first start was about 1/4 mile NW of Cooks runway at an altitude of 1,200 ft.


The second start was over the IP (pattern entry point) for the WSC runway, at an altitude of 1,100. See the trace on the right n this next graphic…


The third start, is also shown on the above flight trace (the one on the left side).  The yellow/red lines indicate noise level (the engine noise).

Both of the first two engine starts were performed at safe altitudes, capable of landing on the runway if the engine had failed to start.  On the third engine start, complacency was clearly a factor.   Although I was near the runway, and I was already at the normal pattern altitude of 1,000 ft, and I was in a good position for an extended downwind entry for landing.  It was not the time to be turning away from the runway and extending drag devices.  On the other hand, starting the engine from this position, relative to the runway was nearly ideal and inherently safe, IF I HAD FLOWN a normal pattern while attempting the engine start. But this is where I made the error.  An error that might have had disastrous consequences if the engine had not started.   I failed to direct the co-pilot to fly a downwind, but simply had him fly the ship as I put my head down and methodically ran the start engine procedure.

This next image shows my position just before the engine started.  FYI, my altitude here is below 700 feet.





On the sat image below I drew a few lines, replicating the flight path.  The white dot between the red line and the pink line below is that same position on the preceding flight log trace, which indicated the position, a few seconds before the engine started.  If the engine had not started, there is little doubt that I would not have been able to fly the length of the field on a downwind and then make a safe base and final turn to landing.  The straight line distance  measures about 3,000 feet, I was at an altitude of about 650 feet and I had the propeller extended/ deployed.  Drag was the equivalent of having the spoilers partially open.

Where the yellow line changes to red is the decision point of starting the engine. Altitude there was about 1,000 ft.  The red line is the flight path while the engine was being prepared for starting. We lost about 300 feet while the prop extended.   The Pink line is the climb – after the engine was started.

The good news is, the engine did start, and we safely continued the turn to the south, climbing and exiting the landing pattern.  This next image is from the flight log and the noise level is displayed, changing from green to yellow as the engine started.

If the engine didn’t start immediately, I probably would have reviewed switch positions (5 or 10 seconds) and then engaged the starter again, (another 5 or 10 seconds).  By that time we would have completed at least 360 degree turn that we were in, and we would have then been once again headed north, or maybe east, and would have then been at an altitude of about 500 ft.  Although it is doubtful that I would have had the presence of mind to do it, I might have make a split second decision to abandon the attempt to start the engine, and decisively taken control of the glider while it was in the turn, and continued 270 degrees, turning on to a final approach, landing to the north, and hope there was no one landing to the south at the same instant.  More likely, considering my mind set, I probably would have initially continued north on the existing downwind, and then momentarily considered executing a low 180 turn to the runway, with a mid-filed touchdown at best, but as I lost altitude, that option would have quickly evaporated.   I may have then have crash-landed straight ahead on the downwind, in the cultivated field abeam or slightly NE of the end of the runway.  Those fields are short and have berms, so that would not have been pretty touchdown and roll-out.  Who knows what might have happened.

A new rule in my mind is… if at pattern altitude, then put the gear down, fly the pattern and land, but it is safe to attempt to start the engine while in the pattern, as long as you remain in a position to land as you attempt the start, and you are clear of other traffic. These are minimum standards.  A better methodology is to be a minimum of 500 feet above pattern altitude when initiating the engine start sequence.  This would allow time for a failed start, and a subsequent retraction of the prop prior to executing a normal pattern and landing.

Is it reasonable to do an engine start when:

  • Flying north along the Mendocino mountains?
  • Flying south to Bessa Dam?
  • Overhead Indian Ranch, or Bear Valley?

The answer locations is  – no it is not reasonable, unless you have plenty of altitude.  If you are within glide range with 20:1 L/D of a landable runway, then it would be OK over those places.  Suppose you try to start, even though you are within normal glide range of a field that is less than 20 miles away.  If the engine fails to start, you may have lost 500 feet of altitude while trying to do the start.  If the engine does not completely stow and you are not back to a clean glider then 20:1 L/D glide may be the best you can hope for.

The reasonable approach to using the motor to divert to the land out field, early enough, while you have enough altitude, to actually get there in a clean configuration, and then, when well within glide distance of the landout field, with plenty of altitude, go ahead and attempt the engine start.   After the engine starts, you then have the option of returning to the flying area or proceeding home.

20 mile circles around landable airports:

Flying north along the Mendos:


Flying south of Goat and St John:



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