I want FADEC!

Hedley · Post by **Hedley** » Fri Aug 31, 2007 5:15 am

DOUBLE ENGINE FAILURE PROMPTS DIAMOND AD PROPOSAL

The FAA is proposing an airworthiness directive (AD)
for the Diamond DA42 Twin Star. The AD would require
additional backup batteries for the full authority digital
engine controls (FADECs) on TAE125-01 and TAE125-02-99
engines.

This action was prompted by the in-flight shutdown of both
TAE 125-01 engines on a DA42 flying over Germany in March.
The pilot of the aircraft took off with an insufficiently charged
aircraft battery. During a moment of low voltage when the
aircraft's landing gear was retracting, the FADEC reset. This
shut down the engines and caused BOTH propeller blades to
feather

Diamond has said that it will cover the cost of the battery
installation, regardless of an AD. For more information, see
Diamond's service bulletin

http://download.aopa.org/epilot/2007/07 ... mondsb.pdf

fougapilot · Post by **fougapilot** » Fri Aug 31, 2007 5:21 am

I would really like to see you fly your routine using FADEC in the Pitts...

rigpiggy · Post by **rigpiggy** » Fri Aug 31, 2007 10:30 am

This happened after the dummy left the master on, started the engines on the booster cables, and took off before the battery had recharged. gear up high voltage draw, say goodbye to FADEC. new technology maybe more efficient but old stuff will tend to give you warning signals prior to breaking

_dwj_ · Post by **_dwj_** » Fri Aug 31, 2007 11:26 am

Even if the pilot was a dummy, this is still something that the FADEC should be able to handle. Apparently this FADEC will reset itself if it loses power for 1.7ms even though it is meant to withstand a power loss for 50ms. When the FADEC resets it auto-feathers the prop, which is generally a bad idea when taking off and especially when it happens to both engines. The battery backup really should have been there from the beginning.

Diesel engines are great in theory - very economical and highly reliable due to less parts. However when you start adding FADECs and turbochargers you're increasing the complexity and potential for things to go wrong. This isn't going to help the reputation of the new diesel aero engines.

Another technology mishap is the Avidyne PFD, which has (or had) a tendency to crash but cannot be restarted in flight.

desksgo · Post by **desksgo** » Fri Aug 31, 2007 11:33 am

I'd like to fly an airplane that when I ask it to do something it thinks about it and gives me the lip of a 16 year old girl when being asked to go cut the grass.

Gear down? What-evar, feather props.

Rudy · Post by **Rudy** » Fri Aug 31, 2007 11:34 am

Insane that they would design it that way. Airplane engines should continue running without battery power. Did they shut down because the fuel injection system needs a battery? Is it the waste gates? Someone please explain.

Hedley · Post by **Hedley** » Fri Aug 31, 2007 11:44 am

Maybe it's just me, but I'd put a big honkin' capacitor - about the size of your fist - between the FADEC power and ground on each engine.

Lommer · Post by **Lommer** » Fri Aug 31, 2007 6:07 pm

Hedly, agreed. A capacitor that could handle a few-second power interruption would be much lighter and more cost effective than a backup battery. But the bigger question is why is the FADEC designed this way!? It's a mission-critical system that has no backup whatsoever and takes 1.28 seconds to reset, which is long enough for the engine to feather/shut itself down. There are serious flaws both in terms of the embedded system programming/design and in the overall architecture of the system. This is a big black eye for diamond in my opinion because it is just plain poor engineering.

kingeddie · Post by **kingeddie** » Fri Aug 31, 2007 6:18 pm

Eurocopter uses a backup called "EBCAU" which is a gear driven device that meters a fixed amount of fuel through the FCU in the event of a total failure of both FADECS. Should be manditory

invertedattitude · Post by **invertedattitude** » Fri Aug 31, 2007 6:43 pm

Relying on automation kills aviators.

rigpiggy · Post by **rigpiggy** » Sat Sep 01, 2007 4:54 am

Most new diesel are of the CRD, or SRD type "single rail/common rail type the old mechanical pump/distributor has been replaced by a pressurized rail w/ electronically actuated injectors. No electrics=No fuel=really quiet. the turbo though an added complexity is normally just a wastegate control as you don't worry as much about overboost as on an Otto cycle

l_reason · Post by **l_reason** » Sat Sep 01, 2007 6:03 am

I spent some time in the UK flying an old 172 that was retrofitted with a FADAC controlled diesel. The engine was smooth, efficient, for the most part reliable. Due to the instillation in the older 172 there were some issues with the fuel pick-ups if you were less the ¼ tanks (2 hours remaining). If a small bubble of air made it down fuel line the FADAC would have a fit and switch to the second computer (sounded like a ½ second fuel cut off). It only happened to me once in flight but was enough to get my attention. Once the engine was shut down it needed to be rest by a factory technician and his laptop. We had this happen 3 times in 2 months over 200 flight hours in two different aircraft once leading to a total engine failure on final (bigger air bubble) 20L was in the tank. Thielert was forced to change the design of the 172 fuel system (adding a second pick up in each tank) to keep the same useful fuel figures they had advertised.

On another note about FADAC controlled engines. These things will make the dumbest pilots ever! IF they are used for initial flight training. With no mixture, prop, or carb heat to manage they may be quickly overwhelmed in an older A/C. The engine “P's” & “T's” are so simple its again too easy to operate, if the LED's are all green you ARE good to go. The pilots will never notice trends or slowly changing temperatures. You only need to look down and see the green to be happy.

co-joe · Post by **co-joe** » Sat Sep 01, 2007 8:08 pm

Diesels don't even require a spark so why would it make sense for them to shut down in an electrical failure? Wouldn't you expect that the LAST thing to keep running would be the powerplant? Obviously designed by engineers, in an office somewhere, who've never been into a cockpit.

Panama Jack · Post by **Panama Jack** » Sun Sep 02, 2007 12:32 pm

invertedattitude wrote:Relying on automation kills aviators.

I know what you mean. Oh, how we long for the days of the LF Range and hand-propping airplanes, when one-armed pilots were men, and goats were afraid.

rigpiggy · Post by **rigpiggy** » Sun Sep 02, 2007 3:01 pm

co-joe wrote:Diesels don't even require a spark so why would it make sense for them to shut down in an electrical failure? Wouldn't you expect that the LAST thing to keep running would be the powerplant? Obviously designed by engineers, in an office somewhere, who've never been into a cockpit.

See last post CRD's use electric solenoid for fuel distribution. Yes, they were designed for cars, mercedes I believe where emissions/efficiency and power are prime, as you can coast to the side of the road if it fails.

niss · Post by **niss** » Sun Sep 02, 2007 5:23 pm

IIRC the way you kill a deisel is to shut the fuel off which is done by way of electric solenoid.

rigpiggy · Post by **rigpiggy** » Mon Sep 03, 2007 7:33 am

rigpiggy wrote:
co-joe wrote:Diesels don't even require a spark so why would it make sense for them to shut down in an electrical failure? Wouldn't you expect that the LAST thing to keep running would be the powerplant? Obviously designed by engineers, in an office somewhere, who've never been into a cockpit.
See last post CRD's use electric solenoid for fuel distribution. Yes, they were designed for cars, mercedes I believe where emissions/efficiency and power are prime, as you can coast to the side of the road if it fails.

God I love wiki

Solenoid or piezoelectric valves make possible fine electronic control over the injection time and amount, and the higher pressure that the common rail technology makes available provides better fuel atomisation. In order to lower engine noise, the engine's electronic control unit can inject a small amount of diesel just before the main injection event ("pilot" injection), thus reducing its explosiveness and vibration, as well as optimising injection timing and quantity for variations in fuel quality, cold starting, and so on. Some advanced common rail fuel systems perform as many as five injections per stroke.

Common rail engines require no heating up time, and produce lower engine noise and lower emissions than older systems.

In older diesel engines, a distributor-type injection pump, regulated by the engine, supplies bursts of fuel to injectors which are simply nozzles through which the diesel is sprayed into the engine's combustion chamber. As the fuel is at low pressure and there cannot be precise control of fuel delivery, the spray is relatively coarse and the combustion process is relatively crude and inefficient.

In common rail systems, the distributor injection pump is eliminated. Instead an extremely high pressure pump stores a reservoir of fuel at high pressure—up to 2,000 bar (200 MPa)—in a "common rail", basically a tube which in turn branches off to computer-controlled injector valves, each of which contains a precision-machined nozzle and a plunger driven by a solenoid. Driven by a computer (which also controls the amount of fuel to the pump), the valves, rather than pump timing, control the precise moment when the fuel injection into the cylinder occurs and also allow the pressure at which the fuel is injected into the cylinders to be increased. As a result, the fuel that is injected atomises easily and burns cleanly, reducing exhaust emissions and increasing efficiency.

Most European automakers have common rail diesels in their model lineups, even for commercial vehicles. Some Japanese manufacturers, such as Isuzu, Toyota, Nissan and recently Honda, have also developed common rail diesel engines. Some Indian companies have also successfully implemented this technology, notably Mahindra & Mahindra for their 'Scorpio-CRDe' and Tata Motors for their 'Safari-DICOR'.

chubbee · Post by **chubbee** » Tue Sep 04, 2007 9:17 am

Battery backup "jetpacks?" are installed in B1900D's with 4 tube EFIS to keep the DPU's(display proccessor's) running under all situations.
Other FADEC's run dedicated PMG's (permanent magnet generator size of a coffee mug, RollsRoyce) to ensure uninterupted power.

Would have thought something similar would have been mandatory original equipment for any FADEC??

Nightflight · Post by **Nightflight** » Tue Sep 04, 2007 3:29 pm

invertedattitude wrote:Relying on automation kills aviators.

Too much BEER will do the trick as well!

. . · Post by **. .** » Tue Sep 04, 2007 3:36 pm

is the high pressure fuel pump electric or engine driven? If the fuel pressure is engine driven it would seem like an easy fix to add a battery backup to the computers. The 1900D EFIS aux power only powers the left side. The right side becomes inop in a dual DC gen failure induced load shed.