Convair 340 (C-131D) ZS-BRV crash Pretoria, South Africa
Ok - so a fact as I see it is all on the aircraft, are related to aviation.
The on board video has commentary - "this is bad"
The focus of the guy that knows it is bad with his camera is on what?
Not the aileron but the engine.
The on board video has commentary - "this is bad"
The focus of the guy that knows it is bad with his camera is on what?
Not the aileron but the engine.
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First of all they had an engine problem from the beginning and secondly the burning engine is a lot more likely to attract attention than the aileron being deflected in an unusual way.
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I tend to agree a disconnect is more probable than a jam, but with fire in that area who knows? Possibly the section outboard of the fire had seized and the section inboard had sheared in such a way that remaining controls were still free. Or vice versa. To really confuse matters, the Convair was built at a time when the FAA, or designers, were going through a phase of favouring rudder/aileron interconnects. The CV- 580 had this, and what awful, heavy controls they were, too. If ever there was a contraption it was the 580.
The centred rudder in the video taken from outside the aircraft still suggests close to symmetric power - whether a lot or a little at the time is not so easy to deduce simply from estimating prop RPM. You'd need to know the manifold pressure and TAS to get a better idea.
The centred rudder in the video taken from outside the aircraft still suggests close to symmetric power - whether a lot or a little at the time is not so easy to deduce simply from estimating prop RPM. You'd need to know the manifold pressure and TAS to get a better idea.
....The centred rudder in the video taken from outside the aircraft still suggests close to symmetric power - whether a lot or a little at the time is not so easy to deduce simply from estimating prop RPM. You'd need to know the manifold pressure and TAS to get a better idea.
My only experience of big radials was the Twin Wasp, half a century ago. But my recollection is that, when the pitch levers are set to full-fine for take-off, the propellor pitch is fixed at full-fine and the RPM becomes a function of the manifold pressure as the throttles are advanced to obtain the rated manifold pressure for take-off. (As you suggest, the RPM rises slightly as the TAS increases.) If that's the case, the engine/prop RPMs are directly related to the power available, and in turn the thrust produced by the prop.
It's not until the first power reduction after take-off that the constant-speed function of the CSU comes into play. The throttle is retarded slightly to the desired manifold pressure, followed by the pitch lever. Once the desired RPM is obtained with the pitch lever, the CSU maintains it for a wide range of manifold pressures by varying the pitch of the prop.
This is from a South African friend who is in the industry:
. Anecdotal info is that a fuel line fractured on the carburetor avgas radial left engine. Fire then burned through the oil lines. Loss of pressure prevented them from feathering the prop. They turned right downwind to avoid crashing into built up areas. I.e. Against the live engine. They set it down on base but hit a single story steel and brick warehouse tearing chunks out and bending the i beams at right angles. Probably with an engine. This effectively broke their speed. Landed straight ahead with both wings separating and burning. All 18 pax WALKED OUT! Pilots injured but not sure how badly.
. Anecdotal info is that a fuel line fractured on the carburetor avgas radial left engine. Fire then burned through the oil lines. Loss of pressure prevented them from feathering the prop. They turned right downwind to avoid crashing into built up areas. I.e. Against the live engine. They set it down on base but hit a single story steel and brick warehouse tearing chunks out and bending the i beams at right angles. Probably with an engine. This effectively broke their speed. Landed straight ahead with both wings separating and burning. All 18 pax WALKED OUT! Pilots injured but not sure how badly.
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The engine put out power at takeoff but was smoking . How about the top cylinder blew head off and broke the prop feathering oil line that runs over the top of it ? Explains trail smoke, engine running for a period, prop not feathering and oil/fuel residual burning in exhaust after shutdown and the windmilling prop. Only a thought....
This is from a South African friend who is in the industry:
. Anecdotal info is that a fuel line fractured on the carburetor avgas radial left engine. Fire then burned through the oil lines. Loss of pressure prevented them from feathering the prop. They turned right downwind to avoid crashing into built up areas. I.e. Against the live engine. They set it down on base but hit a single story steel and brick warehouse tearing chunks out and bending the i beams at right angles. Probably with an engine. This effectively broke their speed. Landed straight ahead with both wings separating and burning. All 18 pax WALKED OUT! Pilots injured but not sure how badly.
. Anecdotal info is that a fuel line fractured on the carburetor avgas radial left engine. Fire then burned through the oil lines. Loss of pressure prevented them from feathering the prop. They turned right downwind to avoid crashing into built up areas. I.e. Against the live engine. They set it down on base but hit a single story steel and brick warehouse tearing chunks out and bending the i beams at right angles. Probably with an engine. This effectively broke their speed. Landed straight ahead with both wings separating and burning. All 18 pax WALKED OUT! Pilots injured but not sure how badly.
.
The centred rudder in the video taken from outside the aircraft still suggests close to symmetric power - whether a lot or a little at the time is not so easy to deduce simply from estimating prop RPM. You'd need to know the manifold pressure and TAS to get a better idea.
The centred rudder in the video taken from outside the aircraft still suggests close to symmetric power - whether a lot or a little at the time is not so easy to deduce simply from estimating prop RPM. You'd need to know the manifold pressure and TAS to get a better idea.
OAP
Was there any kind of data acquisition / recording on board? I understand no FDR in the usual sense but maybe some other device given the engineering related background of the crew?
I would tend to agree with your observation about the centred rudder showing fairly balanced power, along with the limited deviation of flightpath. Beyond that, it is worth noting that engine operating parameters such as RPM, Manifold pressure etc would not necessarily change with a fuel supply or ignition problem. However, the power output certainly does! In this case, there seems to be a certain amount of popping, banging, oil smoke and flame and I guess the crew could tell which engine was in distress.
OAP
OAP
Re the relationship between RPM and power/thrust when the throttle and pitch-lever are set at take-off power, I'd be interested if you and others would comment on my previous post. Assuming the flight crew became aware of an engine problem as soon as they were airborne, I think we can assume that the handling pilot would not have called for a power reduction on either engine until they had had a chance to confirm which one was failing.
Re the relationship between RPM and power/thrust when the throttle and pitch-lever are set at take-off power, I'd be interested if you and others would comment on my previous post. Assuming the flight crew became aware of an engine problem as soon as they were airborne, I think we can assume that the handling pilot would not have called for a power reduction on either engine until they had had a chance to confirm which one was failing.
The complex relationships between RPM/MAP/Propellor/engine controls etc and Power, could fill many volumes. I cannot contradict your recollections of a Twin Wasp installation. However, I am surprised that you refer to "pitch levers" and CSU, when the control for a CSU is often a RPM control. That said, a VP CSU controlled propellor might sit on it's Fine pitch stop when selected to high RPM at low power on the ground but, will subsequently coarsen as required to contain the selected RPM as power/airspeed allow the RPM to rise to the RPM lever set datum-as is the function of a CSU. Likewise, most CSU will simply reduce propellor blade pitch to accommodate reductions of throttle setting or airspeed (climbing) or engine abnormalities like misfires etc to maintain RPM, unless the engine controls are linked. I do not have type specific knowledge of the Convair, so my comments are limited to the generic behaviour of basic piston CSU.
Best wishes to all involved in this accident.
OAP
Yes: sloppy terminology on my part - on the back of 50 years to forget.
For "pitch lever", read "propellor-speed control lever." Re the rest of your post, I won't preempt any welcome comment from others.
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P = propellor pitch
T = throttle/ thrust
M = mixture, it’s a piston donk, yes?
Happy to be corrected by those,who know what they’re talking about, I’m really sorry I missed the era of these flying machines being commonplace,
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Correct. In the CV-340 with the Hamilton Standard constant speed props the RPM / propeller handle will be blue.
No idea if all DC-3 had the white handles as most of them had the Hamilton Standard props as well.
No idea if all DC-3 had the white handles as most of them had the Hamilton Standard props as well.
