The RAT automatically deploys in case of an electrical emergency (losing both AC buses).

It has a generator that generates 15kva for the essential buses, one of them connected to an electric hydraulic pump for the 3rd hydraulic system, for primary flight control tasks. The RAT takes 8 seconds to start generating power, and in the meantime the 2 primary batteries supply electrical power.

If the RAT fails to deploy, the flight crew can manually deploy it.

If all of these fails, including your engine generators, you have a FBW backup battery, that the manufacturer states lasts at least 15 minutes for the elevator and rudder actuators. Note that the ailerons are not FBW, and use conventional cables to command the PCUs.

That's basically how it works.

Does the E-Series have a mechanical backup (stabilizer trim + rudder, like the A320 familiy) or is it a full FBW aircraft ? Or is it even fully mechanical, and no FBW at all ? Even the Embraer Homepage does not say anything...

Indeed it does have a backup battery for the FBW, but it does have a nasty habit of tripping to direct mode when surfaces are exerted to extreme forces.

and yes it does have two modes of operation: normal (FBW) and direct (conventional). Rather than get into an in depth discussion about the control system of the Ejet, I'll say again..mine is just a theory. I think we all really want to hear the preliminary report at the very least. If it's a technical problem, then perhaps it can be stopped from ocurring again.

As Pugachev Cobra said above, the Ailerons are conventional cable/PCU control. Rudder, Elevators and spoilers are FBW. Flaps/slats are electric.

The FBW computers can be deselected and the aircraft can still be flown with certain features disabled (tail strike protection stall protection etc)

If all three hydraulic systems are lost then control is reduced to stab trim and engine thrust.

I noticed in the plane had just been through a maintenance check the day before. No indications of what type check.


This adds another possibility.

Someone on avherald noted it was a simple night service check:

That is absolutely a fair question.
I am posting a screen grab of the face of one of the engines from the video taken at the site, for the purposes of discussion.
http://home.comcast.net/~shademaker/LAM-ENGINE.PNG


The engine clearly shows signs of rotation but the question is, what approximate power setting?

What appear to be the fan blades seem to have taken a lot of abuse, but what appears to be the core engine behind doesn't look as mangled as I would expect from a high power setting.

Maybe somewhere around idle but I don't have much experience in this area.

Any qualified volunteers?

Can anyone tell if that is an engine or the APU ?

Andrasz,

That's an Engine.

Engine is a GE CF34-10E, and the photo above shows the fan rotor disc (hub), with the spinner and most of the fan blades missing. (but why?)

The condition of the LE of the blades says they were abused perhaps by very heavy hail.

Barit1,

Just a question, obviously ice can be very hard especially if cold enough and could be the cause of the LE damage but would not an engine under power pick up debris, rocks etc during the crash sequence with possibly similar effects?

Yes it would. The damage suggests that the engine did produce power at impact.

On a Namibian pilot's forum quoted by AVH it has been reported that the weather was clear at the time of the accident, the line of T/S only moved in later in the afternoon hampering SAR. It appears that weather did not play into this, something seems to have gone fundamentally wrong mid-cruise.

Don't rule out Wx
 

Andrasz, post #32 indicates there was a very active CB in the same time and space that the 190 started descending. Confirmed by Simon on Avherald.
Seems it was CAVOK at the impact site which was approx 70 nm and 12 minutes from departure from FL380 to loss of radar contact which wilh Namibia's Wide Area Multilateration coverage is quite close to ground level.
Initial descent was reported at about 6000 ft/min, and the 12 min total would give an average of around 3000 ft/min. The final resting place was close to the airway and the impact scar in line with the airway heading.
Lomapaseo - Agree that engine photo indicates rotation at the time of impact and barit1- could be hail damage.
So a couple of questions for the 190 pilots.
How many minutes, and how far do you estimate a light 190 would glide with both engines out and RAT deployed - without any pilot input after the first 30 seconds or so. Also do engines remain at idle after FADEC induced relight without pilot intervention.
Maybe ice stopped the engines and broke a windscreen leaving just 30secs to get a lot of things done. Remember thats all you get at FL380 without O2
A possible explanation?

That damage does not look bad enough for an engine producing power, it was probably windmilling when it hit the ground.
Think about it - The pictures suggest that the aircraft was under control and slow when it met the ground. If the engines had been producing power they would not have needed to attempt what looks like a forced landing under control in the bush.

Ancient G,
If they were under control, why head straight on into the bush when Shakawi, 1400m tar runway, was within easy gliding distance from initial altitude departure point?

Sadly we will probably never know the causes.

The investigation will be carried out by Angola and Mozambique, neither of which has a good record for publishing the results of investigations.

Hypothetical Scenario
 

Suppose the E-190 commenced a descent from altitude by bringing the throttles to idle, and the guys flying it were then no longer able to do so (for whatever reason.)

What would the aircraft then do-assuming initially flying with AP engaged?

Best answered by those with experience in that type aircraft.

You might have to add initial conditions of various initial nose down pitch attitudes at the time the crew ceased to function.

The objective is to see if we can create a flight profile that then fits the observed data.:8

Mach,

If they had set alt sel to 0 and press LVL CHG they'd come all the way down. If they had pressed LVL CHG and a certain alt sel (above 3kft) the airplane would capture that selected alt.

The problem is that advertised 6kftpm ROD is an average. It varied much more than that (all I can say).

We have to wait fo the preliminary report to figure what happened. At least to have an hint about.

Yes, to know with some surety as to what happened. Any idea how long that might be? Are the recorders available? Why wait?

Consider this possibility:
Aircraft in level flight in A/P encounters a serous problem (eg Very Large Hail/ Fire in cockpit/ Depressurization).
Throttles pulled to idle and possibly the nose is dropped.
Crew becomes disabled
(Flight control system is C*, isn't it?) (Also works if C*U)
Aircraft slows.
AOA protection limits maximum AOA and aircraft commences a minimum safe speed descent on previous heading. (If C*U, it would be a phugoid descent)
Does this scenario permit the observed arrival conditions?
Can it match the ATC observed ROD?

If a viable scenario, then that might explain how engines could be at low power but still running (if true).

Toxic vapors, smoke, beginning of fire for instance ?