Engine Ops in the ASG32 Motor Glider
By Peter Kelly
Last Edit: 7/03/2017
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, and especially the altitude minimum for inflight starting. The flight manual states that the minimum altitude for starting the engine is about 1,000 feet AGL. More precisely, here is a quote of Paragraph 4.5:
A minimum safe height for extending the propeller and starting the engine
must be met. The criterion is that it must be possible to retract the
propeller again and carry out a normal sailplane out landing if the engine
cannot be started. A general valid value for this minimum safe height is
about 300 meters (980 feet); however, this also depends strongly on pilot
ability and geographic factors.
- 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..
- Hearing Protection: This is NOT insignificant. Besides damaging your hearing, you are also limiting your ability to communicate with the other pilot. Bring along the excellent headsets that Rex has available for your use in this ship, especially if your are the pilot in the back seat. Preflight the operation of the headsets – before you get into the ship.
Preliminary Discussion about the engine getting hot
This info is a bit repetitious to what you will read further on, but you need a clear understanding of this facet of engine operations. I have observed confusion over the past decade on this subject by many experienced pilots that were operating this engine. First, some extracts from the Flight Manual:
Quote from Chapter 3, page 3.15 of the flight manual:
Excessive Engine Temperatures
The Red LED on the ILEC engine control unit is blinking and the display
shows “AIR 126°” or “H2O 110°”.
Reduce power settings and check the fuel pressure. Should the temperature
increase further, stop the engine after having reached a safe altitude
and after having carried out an adequate cooling run, retract the
engine in accordance with the normal check list. Continue the flight in
the normal gliding configuration. Prior to the next flight the engine has to
be checked and serviced if necessary.
Quote from chapter 2, page 2.5 of the Flight Manual:
Maximum coolant temperature: 100°C
Maximum coolant temperature, take-off: 90°C
Minimum coolant temperature, take-off: 40°C
Maximum rotor cooling air temperature: 130°C
There are two distinctly temperatures being monitored: Coolant Temp – labeled H2O on the ILEC/ECU, and the Engine air temp, also called Engine air cooling temperature. In many discussions these two values become somewhat confused.
Coolant/ water temp:
The control of coolant / water temp is not a problem in this aircraft.
You need 40 C min for takeoff because it indicates the engine has nearly stabilized at normal operating temps.
You will NOT have a concern about temps approaching the limit of 100 C unless there is a shortage of fluid circulating in the system.
If you do encounter rising coolant/ water temp and it approaches 100 degrees, there is nothing you can do except shut the engine down, because if you don’t, it will shut itself down as it seizes. The Red LED light on the ECU will blink and show “H2O 110” if you coolant/ water temp is excessive.
Engine Air Temp:
The engine air temp is an entirely different matter. The oil lubricates the bearings and is then burned off as it passes out over the exhaust area. The rotor cooling air temp, otherwise referred to as Engine Air temp has a max limit of 130 C. If you exceed that limit, it may not destroy the engine, such as will happen with a over temp on the coolant/ water system, but it is harmful to the engine, so don’t exceed 130C.
The Red LED light on the ECU will blink and show “AIR 126” if the engine air temp is excessive.
Here is the way I handle high Engine Air temp:
Engine Air temp above 125C?
– don’t panic, but initially, leave the engine running.
– take action
— set throttle at 6,000 RPM in level flight
— Watch for drop in the engine air temp of about 5 C
The point here is that if you maintain current altitude, and adjust the throttle so as to maintain 6,000 RPM the engine is not under much of a load, if any, and the full airflow is helping to cool down the engine. Airspeed will probably be between 60 and 70 knots in this configuration. The manual does not specify an airspeed, but it does specify level flight.
After the Eng Air temp has decreased by about 5 C and you then decide to continue the climb, then do so at a higher than normal airspeed and with an RPM between 6,000 and 7,100. Less RPM, more speed, as needed to keep the Engine Air temp from getting too high. Monitor Eng Air Temp, and keep it below 125, while climbing at reduced power.
If you decide to shut down, then first operate in level flight, with 6,000 RPM until you get about a 5 C drop. Then:
– Fly at circling speed
— set throttle to Idle
— 1 to 2 minutes
— Perform Shutdown checklist
Discussion of hot exhaust temp on the prop and stowing the prop after shutdown.
Quote from chapter 4, page 24.25 of the Flight Manual:
After engine shut-off, the liquid coolant temperature first increases a little,
because the coolant is no longer circulated and the temperature
sensor is fitted directly on the engine housing where it immediately indicates
the engine temperature. As the degree of cooling down is indicated
by this temperature, monitor it closely and wait until the maximum
value has dropped by about 2 °C (4 °F). Only then may the propeller be
completely retracted without any problems.
Note that is says “…wait until the maximum value has dropped by about 2 °C …”
Since the coolant temp will routinely be about 62 C, and then will routinely rise about 5 C to about 67 C, it appears the book allows you to retract the prop fully after it has dropped from the maximum value (which is of 67 C in this example).
In an effort to extend the life of the prop here at WSC, we will note the coolant temp before shutdown and before the subsequent rise in the water temp. After shutdown and while we are monitoring the coolant temp, we will wait for it to drop 2 degrees from the coolant temp that was noted before the rise occurred. In this example we would wait until the coolant temp dropped to 60 C before retracting the prop fully.
The following 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 of 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:
This 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. If you want to climb at a higher constant airspeed, then you need to reduce the throttle as the airspeed increases. When on the desired airspeed, modulate the throttle to maintain 7100 RPM. Definitely respect all RPM limits.
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:
- Fuel – on
- Power – on (ILEC lights)
- Prop – extend (green light)
- Prop – unlock
- Ignition – on
- 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:
“let’s put on the headsets and do a sound check” and you confirm that your passenger has the hearing protection on.
“I am going to start the engine. I have set the flaps to 5, and the speed is 55 kts. You take the controls, watch for other traffic, 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 you 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 the engine air temp is below 110 degrees, don’t hesitate to climb at the best climb speed – namely 49 kts, but once the engine is becoming too warm, adhere to the cruise-climb procedures I have detailed below.
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 – On my checklists, I call this my PRE-START
- Fuel pump #2 on (This is on my ENGINE START checklist, see below)
- Ignition test (6200 RPM/ 300 max drop)
- Engine warmed (40 degrees coolant min)
- Flaps set at Flaps 6 prior to releasing brakes
- Spoilers closed and locked before throttle is advanced
- Hand on throttle during takeoff roll, 7000 Min and 7750 Max RPM limits observed
- Unstick at 43 kts, Initial climb at 49 kts
After takeoff climb
- At approximately 500 ft (This is my At 500 FT checklist)
- Set Flaps 5
- Continue climb at 49 kts, until Engine Air Temp climbs above 110 C
- Fuel Pump #2 Off
- Begin reducing throttle, 7100 RPM before 1,000 ft
- Gear – Retract
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 120 degrees. I target 115 degrees so as to allow some margin below 120. 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 (Green LED). 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
Having accomplished a self-launch, you do not have a tow plane pilot in front of you scanning the area and monitoring for other air traffic. You are continually distracted with monitoring engine temps, RPM and airspeed. You can readily note you may not give your full attention to scanning for other gliders or tow planes returning to the field. Here at WSC the tow pilots routinely announce their position at various times while they are en-route to and from the long tows to Goat Mountain or even to Walker Ridge. There are two clearly identifiable locations that the other traffic can readily identify and a report by you may prove helpful to avoiding other traffic.
There is a section of Hwy 20 on the west side of Williams that is diagonal to that east-west highway. It is seven miles west of WSC. I routinely announce on 123.3 when I am crossing that area. I simply state in the blind:
“This is WS outbound at 7 miles”
There is little need for me to include my altitude in that initial report. If someone wants to know if I am north or south of Hwy 20, or if they want to know my altitude they will ask, but most likely, either there is no one nearby or they already have me in sight.
I make a second radio call as well. The first ridge is 21 miles from WSC. When I am crossing that area I simply state:
“This is WS outbound at the first ridge”
If there is other traffic, they may then report their position, if they think they are nearby and they do not have visual contact with me. Alternatively, they may report they have me in sight. In any case, there is little need for further radio conversation on my part, but I continue to monitor for all traffic. The pilot who does respond to my report will most likely not be the pilot that causes the mid-air. Just because you see one aircraft doesn’t mean there are not others nearby. Don’t get distracted with the radio.
Even assuming you did not exceed 120 internal air temp during the takeoff and climb, you will undoubtedly always need to do a “cooling run” here at WSC. If you ran the engine for longer than 5 minutes you probably hit at least 115 on the Internal Air Temp. Here at WSC I have always needed to do a cooling run.
The Cooling Run
Re-read the above quoted text from page 4.24… specifically….these words:
…. cooling air temperature is over 120 °C… 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.
Thus, if temp is over 120 C, then fly in level flight at 6,000 RPM until temp has dropped about 5 C. That is part one. Part two is as follows. Again quoting the paragraph on page 4.2:
… 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.
Thus, you should now fly at circling speed at 4000 to 5000 RPM for 1 – 2 minutes. If RPM is stabilized, you may then shut the engine down.
In summary, the cooling run, if over 120C, is in two parts:
Level flight, RPM 6,000, wait for 5 degree drop, then do the final cooling step.
If 120 was not exceeded, or you have completed the above 120C cooling run, then complete the final cooling step:
Circling speed, RPM 4,000 – 5,000, 1-2 minutes and look for RPM to stabilize.
- Cool it
- Throttle Idle
- Speed 49 to 54 kts
- RPM – Stabilized
- Note the water temp
- Ignition – Off
- Fly the glider – you are probably in a thermal
- Prop Stop – Engage (ONLY after rotation stops and prop is NOT yet into the vertical position)
- Retract Prop – (after prop is vertical) (hold switch to the beep) Monitor water temp of a decrease of at least 2 degrees C
- Retract/Stow the mast – (after pulsing beeps, and water temp has dropped 2 deg. from temp noted earlier (before shutdown)
- ILEC/ ECU Power – 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.
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.
I have created several checklists for my own use. I use them as a review before flight and suggest that the co-pilot review them as an aid to understanding the procedures. This is a PDF version of my current checklist sheet, suitable for printing in landscape mode and then folding into quarters – so the sheet becomes a narrow strip for your shirt pocket. Confer with Rex to insure you are operating his aircraft properly.
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.
Refueling, Oil Servicing, and Engine Log
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 in the Auto position (if you select “on”, you will overfill and end up pumping fuel overboard onto the hangar floor!)
- 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 about 1/2 of an inch from the top of the reservoir. Clean up any spillage and re-secure the oil filler cap.
- Before takeoff, enter your name, date and the actual engine hours into the engine log book. After landing, enter the remaining information (engine air and water temps and engine run hours).
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.
20 mile circles around landable airports:
Flying north along the Mendos:
Flying south of Goat and St John: