From: bboswell@dante.NMSU.Edu (BOSWELL)
Subject: Re: Another Malibu crash
Organization: New Mexico State University
Distribution: rec
Date: Fri, 11 Dec 1992 20:55:23 GMT

In article <LHE.92Dec4135536@yang.sics.se> lhe@sics.se (Lars-Henrik Eriksson)  
writes:
> 
> Yesterday morning, a Piper Malibu crashed in a residential area
> shortly after take-off from Stockholm/Bromma airport. The three people
> in the aircraft were killed. Fortunately no one on the ground was
> harmed, although it was a close shot. According to a preliminary
> statement by the accident investigation commission, one wing and the
> horizontal stabiliser had separated from the aircraft in the air. At
> the moment, nothing suggests that there was anything wrong with the
> engine. The aircraft struck the ground in a vertical dive.
> 
> At the time, there was strong winds (likely more than 30 knots at the
> surface) and heavy rain in the area. One could expect both mechanical
> and convective turbulence.
> 
> The aircraft was flying according to IFR on a business trip bound for
> Biggin Hill airport outside London.
> 
> As we all know, this is not the first time Malibus crash under very
> similar circumstances. Another Swedish Malibu crashed in Finland some
> months ago. I am beginning to have very serious doubts about this
> aircraft. For some time, I have been thinking on getting a Malibu type
> rating (required in Sweden because of the pressurisation), but I don't
> think I want to anymore.
> 
> I know that the Malibu have been subject to extensive testing without
> uncovering anything wrong, and that a likely cause of the accidents is
> that the aircraft is simply too much for most private pilots. Even if
> this is true, no one really knows the real cause of the accidents, so
> there is no way for me to know if I have the Right Stuff to safely fly
> a Malibu.
> 
> This accident has also stoked the ongoing debate about the future of
> Stockholm/Bromma airport. The airport is very conveniently located
> about 5 miles from downtown Stockholm - but quite close to large
> residential areas. Until the beginning of the 80's most domestic
> traffic used Bromma. Mainly because of noise complaints, virtually all
> scheduled traffic was moved to Arlanda, and the airport became almost
> exclusively a GA airport (it still ranked second in Sweden in number
> of aircraft movements...). Nevertheless, strong political forces
> wanted to close the airport to build apartment houses.
> 
> Following the deregulation of Swedish domestic traffic this year,
> scheduled traffic at Bromma has increased tremendously, and closure
> demands have gotten new strength. A Malibu falling down doesn't
> precisely improve the situation.

One strong suspect in the Malibu/Mirage problems is the autopilot.  This still  
is, however, not a downfall in the design.  The FAA has pinpointed pilot error  
in the use of the autopilot.  It basically gets down to this:

As you know, every aircraft has a maneuvering speed, that is, the speed at  
which you can enter turbulent air and make a full-deflection control movement  
of ANY control surface without causing structural damage to the aircraft.  This  
speed is usually determined at the aircraft's maximum allowable gross weight.

The autopilot in the Malibu ("Maulibu" is a popular joke: it will "maul" you  
quite severely if not flown with respect!) is of the type that can fly the  
plane from point A to point B including ascents and descents if you enter the  
flight plan into the computer.  Pilots have a habit of letting the autopilot  
fly the plane for most of the flight.  All of the Malibu accidents which  
occurred in the U.S.  were attributed to aircraft flown right into known  
class-2 and above thunderstorms (you should not fly ANY aircraft into a  
thunderstorm!!!).

Most of the other accidents were (as I recall; I think I ran across this in  
AW&ST but I can't be sure on this) attributed to entering turbulent air at  
greater than maneuvering speed.  This includes climbout and/or landing  
approaches in the afternoon, when you commonly get the "bumps" in small  
aircraft (thermals too small to affect larger aircraft).  Either the pilot was  
too late in getting on the controls or just let the autopilot do the flying...

Rule #1 of flying (I guess you could call it the golden rule of aviation:)  FLY  
THE PLANE!!! (Or at least be aware of what your autopilots doing!!!).
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