Re: Crash of SR111

Date:         10 Sep 98 03:04:21 
From:         "Craig Beaty" <cmsgbeaty@webzone.net>
Organization: Green Country Flight Training - Tulsa
References:   1
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James Matthew Weber wrote in message ...
>As is my custom in these posts, the usual dislcaimers apply. This post
>involves a good deal of speculation that at least is not yet supported by
>factual material.
>
>Based upon the track of the aircraft,I can't help noticing some
>similarities to the EL-AL Freighter crash at Amsterdam, and some wisdom
>passed on to me by a very senior American Airlines DC10 driver shortly
>before his retirement.
>
>At this stage it isn't clear the initial event was. I suspect some kind of
>power plant problem on one of the under wing engines, probably the right
>engine.

I'm curious, but why did you pick the right engine?  I don't know about that
myself.  The first thing the pilot told ATC is that they have 'smoke in the
cockpit'.  That means one of a few things:  an electrical fire, related to a
system on the circuit breaker panel, wiring and insulation, avionics, or
flight displays.  Smoke related to airconditioning and pressurization
problems would have filled the whole cabin.  If smoke came from one of the
engines, it might be by way of the bleed air for pressurization and air
conditioning.  But, the pilot didn't mention to ATC a problem with either
engine, which I presume he would have if it was the case.   Another
possibility would be a cargo fire (a la Valuejet) which would another tragic
and preventable accident.  I read today investigators have found cockpit
pieces with heat damage.

Ergo, SR111 should have made
>the dive for the runway, and not bothered to try to dump fuel and carry out
>any sort of maneuvers. The high speed descent would probably have also
>prevented the sequence of events that probably resulted in the crash.

I wonder under what configuration and altitude they are approved to dump
fuel from.  They (the crew) mentioned dumping fuel at 10,000 feet, and I
presume, level flight.

>>Exactly what goes wrong isn't clear, at this stage, but things obviously
>did go from bad to worse (pilot's call goes from level 2 emergency to level

>1), and my guess is that is the point at which one engine really does pack
>it in, and probably takes one of the hydraulic systems with it.

Even if one engine did 'pack it in', the plane would still have plenty of
backup hydraulics (I don't even think one of the hydraulics systems would
fail) and plenty of controllability.

>Observation 2: All jetliners since the 707 have incorporated a feature
>called a rudder ratio computer.

Does the 727 have a rudder ratio computer?

>The Rudder ratio computer masks the loss of rudder efficiency with reduced
>airspeed until the rudder authority is GONE. In theory if you keep track of
>minimum control speed this doesn't happen, however it is obvious in the
>heat of battle, this very important issue seems to have been lost several
>times. If you look at the crash of the El-AL 747 freighter, it is clear the
>crew losses control of the aircraft, and in fact I believe the FDR showed
>that at the time of the crash, the aricraft was in fact below minimum
>control speed.

The way I understand your explanation of the rudder ratio computer is that
at lower airspeeds for the same rudder pedal deflection, the rudder actually
deflects more.  If that is correct, that is the way it's supposed to work.
You still have the maximum amount of physical rudder travel available at low
speeds, the deflection and effectiveness of which the engineers properly
designed and passed certification for.

The El-AL 747 freighter lost control, as I remember, when two (of it's four)
engines on the SAME SIDE departed (fell off) the aircraft on takeoff (either
that or the two engines had complete failures at the same instant).  The 747
is not capable of a two engine on one side only climbout, as they tragically
learned.

>My suspicion on SR111 is in the descent with the loss of the engine, the
>crew lost track of minimum control speed, and lost the required rudder
>authority.

There is absolutely no hint of engine malfunction so far.  They had a fire.
In the cockpit.  In hindsight, they should have gone directly for the
airport in a high drag emergency descent.

>As I mentioned previously, this analysis is highly speculative, and at
>least at the moment there is not a lot of data to support the hypothesis.

Yes I see.  Nevertheless I was temped to respond.   let's hope the CVR
lasted longer into the flight than the FDR.

Craig Beaty
CFI ASE, ASMEL
Tulsa, OK

"If you want to be a pilot, you have to act like one;
if you want to act like a pilot, you have to think like one;
if you want to think like a pilot, you have to study like one."