407 Fadec
 

407 single channel, 130 twin channel

Hmmmm .... The 407 RFM states that with FADEC software 5.356 installed, "the engine uses a digital electronic control system based on two electronic governors called a primary channel and reversionary governor. The primary channel is a full-authority digital electronic control (FADEC) that controls, monitors and limits engine power while maintaining rotor speed. The reversionary governor can automatically take control of the engine in the event of a primary channel failure."

It is my understanding (possibly incorrect) that 5.356 software is installed on more recently produced aircraft.

That version software is certainly installed on aircraft from November 2008 on, not sure when it started on new production aircraft. There is a new software version, soon to be released per the Bell Training Academy, that will further reduce the type sensor failures that will cause a switch to manual mode.

The reversionary governor campaign on the 407 swaps out the A250-C47 FADEC's EMC-35A with the EMC-35R, a software change which incorporates the switch from single channel to dual channel.

The Arriel 2B1 on the EC130 (and later AS350B3s) features both a dual-channel FADEC and an independent automatic back-up channel.

I/C

Just received revisions to my RFM/MD today, and this is apparently 5.358. A quick read indicates that this has substantially the same dual channel capability as 5.356, but with some tweaking of certain parameters. Example: NG at which FADEC does auto relight test is 55% for 5.358 and 50% for 5.356. There are several similar tweaks. Will be at BTA next week and hope to learn more.

B407 FADEC Software
 

Have been at Bell Academy this week for B407 recurrent and received a good dose of FADEC related information which I have summarized below to the best of my ability. The experts may wish to add or correct as appropriate.

Software version 5.358 is now installed in newly manufactured helicopters and a RFM/MD revison was issued recently to cover the changes. The changes in 5.358 are primarily aimed at reducing the instances in which the FADEC reverts to manual control (direct reversion to manual). Software 5.358 (and 5.356) incorporate a software reversionary channel which can take control of the engine in the event of a primary channel FADEC failure. This reversionary channel is limited in its capability (but the FADEC remains in AUTO mode), and does not support:
1. Automatic start with starter and ignition operation
2. Ng power modulation based on Power Lever Angle (PLA)
3. Temperature limiting
4. Automatic relight
5. Surge detection, recovery, and avoidance
6. Quiet Mode

Some RR data was presented which indicates that reversions to manual have been reduced by up to 70% (depending on which software version one is comparing to). :ok:

The Arriel 2B1 carries 2 fully digital and independant lines within one DECU. If one fails, there will be no degredation of any engine performance as the other channel will take over with full authority. Upon shutdown the pilot will get an amber GOV light to inform him one of the lines were/is unhappy with something. It will give him a full flight report and for the technicians a maintenance screen is available listing fault codes with a list of posssible components causing the problem in sequence of probability. The code refers to the Maintenance manual were the fault finding steps are laid out step by step. Also, the 2B1 does it's own power checks and compute your margins. The DECU and VEMD is biased towards atmospheric conditions so the displayed fLI(first limit indicator) already takes atmospheric conditions into account. The vEMD also allow you to enter weight, alt, temp and will give you your IGE and oGE weight limits before and during flight.

If both of the lines fail you have a 3rd system called eBCAU which will regulate N2. The pilot will get a red GOV and the procedure is a caution to not do radical collective changes as the EBCAU does not read the collective as the 2 DECU channels does but it will govern the engine.

The nice thing about the 2B1 are the alternators driven by the engine(N1 signals). These power the engine and DECU so even if you have a full aircraft electrical system failure, the engine will retain full authority.

A generally similar arrangement on the 407: an engine (Np) driven permanent magnet alternator (PMA) powers the FADEC (with NP > 85%) in the event of an aircraft electrical system failure. "Full authority" is retained unless there should also be a FADEC failure.

victor papa,

I can only prosume that the DECU that you reffer to is the same as the DECAU ??
Not being sarcastic- just checking if I was given the right info?


Cheers
DC:ouch:

Dynamic component-I just double checked and it is according to Eurocopter called a DECU for Digital Engine Control Unit. The EBCAU is Engine Back-up Control Ancillary Unit.

I will double check tomorrow the Turbomeca books-one never knows with the French:rolleyes: but generally the A would be for ancillary which the DECU definately is not.

That would be NP, not NR.

It's actually N1 that drives the backup generator unless my memory is wrong.

For some of us (myself included) the memory is a bit weak; according to the BTA 407 Pilot Ground and Flight Procedures training notebook, "The Np (N2) gear train drives the PMA, the torquemeter, and the freewheeling unit." Its not N1 (Ng) or MRGB. Vaqueroaero wins a new 407! :ok:

victor papa,

My bad:O
Just double checked my manual.
Had the DECU and EBCAU confused:D

Cheers
DC

Thanks EN48 - just shows what relying on - what were we talking about again?

407 track and balance
 

RADS versus Microvib or some other system?
We use the RADS for 407 M/R track and balance and I want to throw it in the river. Tail rotors are not a problem. Rotor smoothing after major hub work makes me want to kick the dog. Anyone have any sucess with using a different system other than RADS on Bell 407's? We are looking for any input. If its not tracker problems, or garbage solutions that do not make the vibration levels better, its interference from the Air Conditioner, the Garmin GPS, the Transponder, etc etc. Looking for your input.

Besides the 407's we also have L3,L4, B3, and do work on R22,R44, Enstrom 480B. Looking for a system that could handle all these helicopters.

Vibrex 2000
 

Have been using vibrex 2000 on the 407 with no problems.
Fit reflectors to the blade tips and track as normal
Uses fore and aft accelerometer and one vertical accelerometer
Contact me for more info

Good news from Heli Expo:
"Honeywell Announces HTS900 Engine Upgrade For Bell 407 Operators" :ok:

I understand that a few days before HAI, Bell finished performance charts that will give increased numbers for greater than a min spec engine. While an L4 is generally torque limited, the 407 is often temp limited making this welcome.

Buzzing 407 rotor tips
 

I had a strange thing happen yesterday and was curious to see if anyone knew what had caused it.

Tied a Bell 407 down to the helideck yesterday, normal construction, 60x60 ft, in the face of an oncoming thunderstorm. After it passed about an hour later, I went to untie the machine with a couple of guys based on the platform. Getting to the aircraft I noticed a buzzing sound but assumed it was the lighting round the deck. One of the guys untied a blade and asked me why it was making that noise. Sure enough, it was the tips of the rotor blades themselves making a buzzing sound like standing under high tension electric cables. We got a step ladder and there was no damage to be found, and no water coming out of the vent holes. The noise was coming from each individual tip, and was audible approx 6ft away from the machine. The battery was off, and the blades were all handled (carefully!)so presumably grounded, and the noise continued for a good 20 mins or so. Engineering guessed maybe a harmonic vibration from the platform, but never heard anything similar before.

Any ideas?