Hydromechanical FCU and Combustion Air
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- เผยแพร่เมื่อ 17 มิ.ย. 2024
- A brief description of hydromechanical fuel system components, as well as a little review of the combustion section of a gas turbine engine.
Also have a look at my recent video called Combustion Pressure: • Combustion Pressure in... - ยานยนต์และพาหนะ
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Had a 747 a few years ago that was waiting for a gate for over an hour. Temps were around 5F and it was snowing. After about 50 minutes of running at idle the #1 engine rolled back no messages on the EICAS. A few minutes later #2 then #3 and finally #4. Pilots were supposed to run each engine up above flight idle every 15 to 20 minutes or so to keep the case warm enough to keep the P1.5 passage from the inlets from freezing up. Took over 48 hours to thaw out the engines enough to get the engines to start. No hangar space available and temps dropped subzero and we had to use torpedo heaters to warm up the HMU's and tried blowing out the lines with nitrogen. It was quite a project.
I helped my mom make chocolate chip cookies this one time. I did all the stirring and taste testing!! That was also quite the project.
Hah, nice to see the Nene 10 graphic. I worked on CT-133 Silver Star for a couple postings during my career in the CF. License built by Canadair, we put the Nene 10 in it vs the Allison in the Lockheed version. Quite a few examples still flying today under civilian registration.
At the end of my career I worked in support of the CH113/113A Labrador Helicopter SAR fleet. GE T58 powerplants. Same powerplant as in the Sea King but because of the length of the aircraft control of the FCU was electro-mechanical vs strictly mechanical throttle linkage. Most helos have an extra switch on the collective to fine tune rotor rpm called the 'beep' switch. Rotor rpm being critical & ideally kept at 100% will be one of the primary 'signals' to the FCU. As pitch is increased/decreased the FCU must react almost instantly to prevent rotor rpm 'droop' or overspeed. A lot going on there. The CH113/113A has 2 separate Engine Condition Control systems to run the FCU. If the primary system fails the pilot can switch to the Emergency Engine Condition Control system. Both are electronic but the Emergency System is very direct & touchy, if the pilot is not careful it's very easy to overspeed or stall the engine. With the normal system any movement of the collective (change of rotor pitch) is automatically taken care of. With the emergency system the pilot has to change throttle setting with any change of collective to maintain optimal rotor rpm.
In my vid called Warbird Jets, we are riding in an ex-RCAF CT-133, and flying along with an ex-USAF T-33. That was an amazing day.
@@AgentJayZ I was fortunate to score quite a number of back seat rides during my Germany posting. Memorable & amazing for sure. The old T-bird is quite nimble as I found out after we were 'bounced' by a German F4 Phantom. After the initial embarrassment of getting had the pilot got on his tail & the only way the F4 could shake us was by lighting up the afterburners & leaving us in the dust. I was sweating the proverbial bullets....
Yeah your videos got my just graduated nephew on his was to the BCIT turbine maintence program thank you!
I was in GT-19 at BCIT
I've overhauled many PT6A, PT6T and M250 series controls and I can tell you they're all not the same and are complicated as hell. Many people thing FCU's are just a general and repetitive process but I can assure each one is unique for sure. The most picky is the PT6A-42A FCU. We've been back aft forth with Piper, Pratt, and Honeywell and no one knows how to set them up. From our calibration limits to rigging it up and flying it's the one that gets the most gripes after being tampered with on and off the airplane.
Yes, when I say what I always say, I mean that they all perform the same function, but every type of FCU is completely different from all others, sharing no parts.
I worked in a diesel engine development lab. We had one guy whose full time job was adjusting injection pumps.
I like you noted Burner and CDP essentially the same thing. I never thought about that before. I do remember either way a leak in that sensing will give you a boat load of problems from hung starts, failure to set trim, and engines that flameout when snapped to idle.
I find analog computers really interesting. This was a great overview that, although greatly simplified, was just inside my ability to understand. Thank you! For those who like analog computers, and no nonsense channels, consider checking out Curious Marc’s 5 part series on the restoration of a Bendix air data computer.
Hey old friend! I was lucky, my background in automatic transmissions gave me a decent head start on figuring these things out. If you ever get to the Augusta Georgia area, let me know!
Luv seeing you still sharing your wisdom and experience. :) Is very cool!!!
Rare opportunity to look inside a fuel control. Very good!
Regarding to FADEC control. If somebody understands the older hydromechanical control its very easy to understand Fadec. Its does the same but in a much straight forward and technically meaning cleaner way. AgentJz if you need engine manufacturer training manual about cfm 56 or Cf 6 fadec engines let me know. Good explanation of fadec systems.
I would tend to disagree with that but only from the point of view of experimental engine testing. When we tap into the EEC we can adjust fuel ramps, LUFF, TCC, trim VIGV and VSV angles, toggle system valves the list is huge. At face value the simple side of the EEC and EMU seems simple but at depth iys just as much fun as trying to set a hydromech governer on a mk103 Pegasus the main difference is with FADEC once you commit the trim you are committed to the result whereas trimming hydromech is a bit more incremental.
@@paulpower3766 my comment / experience is from aircraft maintenance side not from engine / engine control overhaul side.
Could I somehow get my hands on cfm 56 manual? Im airceaft maintenance student, and I could maybe find something useful.
The training manual is a 24.00 download at eflightmanuals.com
@balazsegressy3788 Yes when you have to live with continued airworthiness requirements besides a change to the datum plugs you wouldn't want to do much else. In theory though if the airframers had an odb style plug in port you would be able to carry out the ground runs through a laptop on autothrottle, wouldn't check any cockpit controls or linkages though.
When I was a child dad brought home a part of a discarded unit for me to play with (Input drive, flyweights, power lever and some membrane input if I remember correctly. I was astonished of how smooth and nicely it spun, sadly I haven't kept it. Most likely from an RM8 or RM6 (Volvo Flygmotor).
We've got half a dozen RM6C engines in storage.
@@AgentJayZ Yeah I saw that mentioned in an earlier video... My "want-organ" is twitching, luckily I'm not completely insane (yet).
Draken is also my favorite jet, such a beautiful kite.
They call that bellows thing an "aneroid capsule".
They're used in altimeters too as they get longer when the static air pressure drops with altitude.
I still have a brand new boxed fcu for my Palouste engine, a mechanical work of art
Thanks you Jayz
Kommandogerät für Flugmotor BMW 801 would be an ancestor of the hydromechanical engine fuel control( FADEC as well).
There is also Kommandogerät for weapon system, to alleviate confusion.
Rolls 250 C20 FCU is something like 320 individual parts the one time I counted. Those are about as simple an FCU gets. the C47 HMU's are at least 3 times that.
THANK YOU AGENTJAYZ
Engineers are insane... I liked math but this is pushing my limits how they made this stuff.
It is not "like" an analog computer - it IS an analog computer
Yes, you are right!
@@AgentJayZ it always amazes me what had been done the carefully tuned analog way and now is just thrown on with digital computers
would that be like the EuroCopter catastrophic crash where engine ran until firedept doused it with a couple of hoses? "On May 30, 2008, a Eurocopter Deutschland EC135 P2+ crashed in Pottsville, Pennsylvania ¹. The pilot, flight nurse and flight paramedic survived the crash with minor injuries. The crash occurred due to the pilot's inability to shut off the left engine after the crash. The pilot tried to put the engine to idle, but the seatbelts were locked, preventing him from reaching the switch panel. The left engine was eventually shut down by the fire department by flooding it with water ¹.
Didn't know about that one. There was a large twinjet that firehoses could not help. I took a lot of foam to finally get it out.
Also Qantas flight 32, an A380 that suffered an uncontained #2 engine failure in 2010. #1 engine could not be immediately shut down after landing, due to fuel and control system damage. Emergency crews doused the engine and it eventually shut down.
Thanks
Hi Jay, I have a question that I hope you would do a video on.
How does a mechanical fuel control unit know how much fuel to inject at different altitudes (air densities), since there has to be a sweetspot/target Air/Fuel Ratio for maximum efficiency/power.
Also, since piston engines lose power at high altitudes due to a low(er) amount of oxygen, surely jets experience the same, correct?
p.s. this question may sound very clunky and I apologize for that but I havent slept in about 24 hours and I wanted to post this comment before I forgot about it
It's the subject of the vid. I explain it a little bit, and encourage further reading.
Is it true that a jet turbine can consume all kinds of fuel such as regular diesel and gasoline, almost any liquid that burns?
Yes. With minor adjustments, any fuel will do.
@@AgentJayZ Thanks for answering JayZ. How come turbine engines can burn a variety of fuels so easily?
@@diemc7a1 I'm not an expert, but I think because they're much less sensitive to the details of the combustion process going on in the combustor, it just needs to heat the air to an appropriate temperature, causing it to expand and accelerate in the process. You can even swap out the combustor for another heat source like a nuclear reactor, the rest of the engine won't know or care. The combustion is also continuous, so ignition is not timing-critical and only a worry for the start process but not when it's running. In contrast, a piston engine needs the fuel-air mixture to ignite extremely consistently at the exact right time, and is also sensitive to the burn rate since this affects cylinder pressure (since it's a confined space) and thus how much force is applied to the piston at what time.
Do these fuel modules "monitor" fuel pressure?
Fuel is supplied to the FCU at up to 1500 psi, and is modulated to a delivery pressure to the fuel nozzles up to 950 psi. The delivery pressure is modulated with respect to all of the signals monitored, especially the power lever angle, set by the pilot.
Why would they design in a manual emergency fuel control rather than just adding a second, backup, automatic fuel control? Cost? To remain functional in the event of “sensor” (flyweight, etc) failures?
At the time (1950), the "automatic" control of throttle, temp, rpm, and all that was a new thing. They must have thought that the backup should be full manual control.
Nowadays, I think your idea is the way it's done.
You sound so different than 201”! (Turbine engine)
9:06 Hi AgentZ today my lesson at easa part 147 was about FCU and if i remember correctly that bypass you refer is to prevent pump cavitation. Correct me if im wrong.
No. Pump cavitation is not a thing, but pump starvation is prevented by the boost pumps, which are in the fuel tanks, and typically maintain 3 to 10 psi in the supply line to the inlet of the fuel pumps.
That weird bypass was illustrated in the delivery line to the fuel nozzles, after the fuel control. Never seen such a thing.
@@AgentJayZ Thanks for reply. Now I am curious about this fuel control sistem, although it is outdated, I'll try to learn it so my overall understanding gets better.
I came in expecting this would be even more complicated than an automatic transmission but it's...simpler?
I've taken apart and rebuilt a 4L-80e. It is as complicated as a mud brick compared to the Orenda (1947) fuel control. As mentioned, we see only a brief glimpse of a couple of pieces here.
So the answer is "Don't Ask!"
I bet after this video, China’s 6th Gen fighter will have a hydro mechanical fuel system. 🤣
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