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Diesels- mechanical vs electronic

  • Thread starter Thread starter SKYCHENEY
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Ah, this thread brings back fond memories... when I was in college (1964 or 1965) studying EE I had to do a senior technical paper...so I chose "electronic ignitions". At the time they were not widely used, but I had a contact in North American Phillips whop had access to lots of then current industry data.

At that time transistors were being tested and used to replace ignition points and their attendant arcing, pitting and performance degradation...what turned out to be their achilles heel was...temperatures!!!...they failed because it was hot in the engine compartment. So my conclusion was "NOT YET READY FOR PRIME TIME"

Fast forward about ten years: I was crossing the George Washington Bridge in the mid seventies in my 1969 Corvette...when it died on an exit road in NYC!!! So it sat for two weeks in a local garage because when they took out the old electronic ignition and replaced it....nothing!! engine was still dead...??? Then the mechanic had the insight to order ANOTHER new electronic ignition..PRESTO all was well...my old one failed, the first new one was defective.....

So current bugs and failures may be worked out over time. I'd be equally concerned about software issues: I know damn well this computer sometimes does what it wants. And of course that 660 HP Cat I saw two years ago "dead in the water" because it's twin sprayed water on the "waterproof" electronic control box would also benefit from some design changes. Engineers, software or other, aren't always THAT bright either.
 
krush said:
I worked at GE Aircraft engines on the CFM-56 (it's on 737's, A318/99/20/21, A340) and learned all about the engine and the computer controls. The computer was double everything and I think rotated "who was in charge" on each start. It cross checked itself and if one was screwy, it would use the other computer.

I operate both hydromechanical and FADEC Rolls engines and you're correct, the electronic engines use dual channel everything and swap each start cycle. They also have an alternate mode which is used when say an EPR sensor fails. As for malfunctions, there are fault warning computers (measuring parameters and flagging faults) , flight data recorders that record the big picture (engines, throttle position, flight control position, etc.), and cockpit voice recorders to capture the "OH SH*T". I can also "snapshot" the aircraft when something screwy happens and our mechanics can download everything. Cool stuff, very reliable.
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Maybe its the wrong mindset but I would rather be able to fix or adjust something than need to bring it home on one wing ( if possible) to get it fixed. If I could reset the computer on the water I would look at it differentially. Even if I could run it from a laptop in an emergency. That said the old Detroits run too good to complain about.
 
There seems to be a fair bit of disagreement among people with regards to exactly what happened in that 777 incident.....

But..... a look at the pictures that have been posted sure leads a reasoned person to believe that the engines were not developing power at the time of impact......

So what kills BOTH engines? Fuel problem perhaps eh? Now the obvious question is whether the pilots literally burned up all the fuel or whether something disrupted fuel flow into BOTH engines.

Hmmmm......

I'm sure we'll eventually find out - but I don't buy "computer failure" for the reasons put forward (ONE engine failing, yes, but BOTH at the same time? Hmmmm again....)

All I know is that when I'm 100nm offshore I like the idea that my running engines, absent GROSS mechanical failure or running out of fuel, will REMAIN running.
 
rob, NEW stands for Never Ever Worked.

One of the reason the early Jaguar V12 had a reputation for unreliability is that the OPUS electronic module (state of the art back in 71 and derived from F1 technology) was located in the vee behind the AC compressor. no air. these things woudl cook in there till failure. First thing i did when i go mine 9 years ago was yank the opus and mount an MSD6 somewhere else. problem solved.

Computer problems on that 777 could be more than the engines computers... i dont' know what is between the engines and the power levers but it's obvioulsy not cables! Remember that first Airbus crash during a air show in france, they made a low pass but the computers "refused" to increase power and they end up landing in the forest at the end of the rwy? forgot the details but the flight computers assumed that they were landing based on flaps, gear, angle of attack and didn't let the engines spool up.

http://www.youtube.com/watch?v=BxP8LwSArYA


the problem with computer controls, in cars or boats, is that they dont' always record faults and when that happens the mechanics... sorry.. the technicians are completly lost and clueless. Their only way out is to throw parts at the problems which is ok under warranty but gets real expensive otherwise.

on boats, it's comforting to hear those DD runnings and knowing that even if you loose all electrical they will still be running. Heck you could probably gravity feed them from a bucket !

yes they're noisy, often leaky, and not environmentally correct... but you're not at the mercy of a computer. and don't get me started on electronic controls vs cables ! :-)
 
The reports said the engines were at idle but not dead. Electronic issue? Could be. Remember a few weeks ago when a 747 landed on emergency buses after ALL generators failed? No, the genny's didn't fail but the generator controller did after a crack in a drip pan allowed stray galley water to drip onto the controller, zap. Will be interesting to find out what happened to the 777.
 
Mike, what do you fly that still uses hydromechanical? I thought airlines have tried to phase those out because FADEC offers much better reliability and it eases pilot workload....just slam the throttle forward all the way for go!

If you were Air Florida Flight 90, would you have slammed the throttles forward?
 
The whole feeling re computer-controlled engines in a boat is probably related as much to the boater's view of boating as anything else.

I like the mechanical related aspects of the process and the "bring-'em-back-alive" mindset has a lot to do with it - at least for me. I want to be able to understand and repair every aspect of my boat because TO ME, that is one of the most enjoyable and satisfying part of boating - the fact that I don't have to rely on ANYONE else. There's just me, my wife, the boat, and my tools/manuals!

If I couldn't do all the work, I wouldn't enjoy it nearly as much, if at all.

I like mechanical things - I can spend hours looking at old steam locomotives and just marvel at the mechanical nature and complexity and inventiveness of humans in general.

But again, this is all personal and we all bring our own personalities (or lack of one!) to boating or anything else we do. Heck, I'm always after the latest computer stuff so I love that too - just don't want my Imac to control my DDs!
 
krush said:
Mike, what do you fly that still uses hydromechanical? I thought airlines have tried to phase those out because FADEC offers much better reliability and it eases pilot workload....just slam the throttle forward all the way for go!

If you were Air Florida Flight 90, would you have slammed the throttles forward?
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Gulfstreams. The Tay 611 (G-IV) and the BR-710 (G-550). I wouldn't say mechanical fuel delivery is less reliable than FADEC, just better on fuel. As for flight 90 it's tough to Monday morning quarterback, many links in that error chain. When flying hydromechanical engines pushing the power levers full forward can get very expensive (overhaul?), thats why pilots are reluctant even though we train to do it in the simulator. When it come to marine I love my mechanical Cummins, with spare parts and a box of tools "I" can fix it.
 
Like MikeP said a lot of your opinion about this issue is mindset. I too can marvel at the mechanical complexity of an old steam locomotive for hours. I want to be doing my own maintenance and be familiar enough with all of the aspects of my boat to keep it afloat and get it home in an emergency. I don't want to depend on a non user repairable black box that has not, in my opinion had enough R&D for me to depend on it offshore. The systems in boats are not as dependable as those in aircraft but are more comparable to those in automobiles. And we NEVER see those on the side of the road.
I will stick to my old mechanical DD's at least for now.
JMHO, Fred
 
Maynard Rupp said:
I wouldn't be so quick to blame the 777s computers. As a professional pilot, I looked into that and pretty well have decided that the crew had their heads up their, well you know where.
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It's sad how the media hails these sort of idiots as heros for surviving the results of their mistakes. Remember the morons who let the Airbus run empty over the Atlantic? They were able to glide to the Azores and make a safe landing where they were cheered not arrested!
 
MikeP said:
"Question is: Why didn't they ground the entire 777 fleet while they figure out what happened?"

I suspect that they DIDN"T ground them because they have already figured out that it wasn't an "airplane" problem which leaves a crew or a maintainance-related issue. Either that or Boeing has so much clout/influence that they have prevailed upon the powers that be to NOT ground them. That's too scary to even contemplate...
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It wasn't that way back in the '70's when they grounded the whole DC-10 fleet over an American Airlines repair procedure gone wrong.
 
Interesting thread for an old Boeing engineer and a new Hatt owner comtemplating repower.
First, folks need to let the investigation be completed and the report to come out on the 777. This isn't politics or war; the truth will be known soon enuf. As a retired 777 pro, what I noticed is how the gears snapped off just as they should (fuse pins) preventing rupture of the tanks and how all the escape slides appeared to deploy perfectly. These standard and FAA mandated features cost the airlines billions per year in equipment costs; this event shows why the regulations exist.
While investigating repower options, the Yanmar dealer showed me a Volvo Penta "black box" and 3 dead shift actuators from an electronic diesel. He said the black box was $1500 and the actuators were $700 each. The issue was still not resolved and he said that the VP people were stumped. I believe I will go mechanical which is still an option with Yanmar and Cummins. If the electronic stuff is so good, just show me a 10-year free replacement warrenty on all the electronics!
Gary
 
No one will gaurantee ECM's or sensors for 10 years,but the electronic diesels are that good. What I recommend to my customers is to carry a camshaft position sensor,oil pressure sensor and coolant temp sensor on the boat.All three are sensors that go to the ECM,not the gauges. When an engine disabling problem occurs with an electronic,those are the sensors most likely to fail.You can still get home with a bad injector,but having a spare is good. A few of those owners already own the engine manufacturers software and it is hooked up to a computer either on the bridge or readily available to scan codes.

As a guy that has made my living with diesels,even hotrodding and drag racing big diesels,electronic controls have made possible what used to take us years to perfect with mechanical engines and are far more durable. Sensors or ECM's can fail but these engines at much higher horsepower ratings, can far outlive mechanical engines. Tony
 
Slightly off thread, but I had one of the afore mentioned early '70's ECM Mercedes. In those days, MB didn't make anything simpler, when more complex was avail. So instead of going all electronics, they inserted the old cam actuated "points" in the logic and the points ran the ECM. In reverse logic, it was not documented that they ran a special chrome plated points, because the very low amps in the new system didn't "burn off" the points. So most dealers installed the wrong points that got oil and flaky.

Did I mention that heat (see other posts) ate the ECM's, which would then stall the engine when most inconvenient, usually in traffic (ibid). The founder of the Ziebart Undercoating was Kurt Ziebart, originally from Germany. He got into undercoating, because he was trained in body repair and rusted hulks were illegal in Germany, but common in the US. So he developed the undercoating process. He bought the Mercedes-Benz Dealer in Acme, MI (Traverse City), when he sold the undercoating for franchising. When the topic of the ECM's came up, he would say "ja, ja, ja, day all going bad all over...day are tearable...dying everywhere. I put da old good points systems in dem."

I love drop forgings. I have drop forged brass doorknobs in my house (a fetish?). So I found it interesting that the hot new Ford GT's had sintered metallic steering and idler arms (both connect to the steering box to the front steering linkage...sort of important at 180mph). They all snapped in half at 5mph, usually when driven out of the dealer. Guess what...drop forged arms went in there. So I related the forgings to the electronics...one is very sturdy, the other much less so.

EMP mentioned above. If that EMP truly happened (the electro magnetic pulse from a nucular [sp? sounds right!] weapon explosion) all the US would be DOA. Several well positioned weapons over the major megaoplis about 20 miles up each would do. Virtually all electronics except hardened military gear would be fried. But our old Hatt DD's would start and run just fine! Geez, I hope I don't get a call from a Federal agency for that post.
 
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The government has rebuilt and warehoused tons of old tube radio equipment. Just because of EMP. They found out that at the beginning of the Gulf War the newer radio equipment was failing because of the static buildup from the blowing sand. They could not get there hands on enough R-390 tube radios. If we get bombed. Who the hell is going to be around to care?

BILL
 
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