|POINT AND COUNTERPOINT. The FAA issued an Airworthiness Directive mandating special crew training for Boeing 737 pilots in the event of a rudder system malfunction, and subsequently issued another A.D. requiring various modifications to the 737's rudder system.
February 10, 1997
Vince Massimini — an ATP, retired military pilot, and aviation consultant in Washington DC — feels that T. D. Ponder's approach to this issue is counterproductive. Massimini says that until the NTSB, FAA and Boeing are able to figure out the cause of the fatal 737 crashes at Colorado Springs and Pittsburgh, cries for action and anecdotal pilot stories don't do any good.
I must take issue with
Mr. Ponder's guest
There is little doubt that the B737 rudder
PCU has known rudder problemsbut
they should not upset the aircraft.
Until the recent tests at very extreme
conditions, no one could demonstrate any
rudder malfunction that could have rolled
USAir in Pittsburgh or United in Colorado
Springs into the maneuvers that resulted in
the crashes. The conditions that finally
produced a malfunction were so extreme
that it is very unlikely that it was the cause
of the USAir crash at PIT or the UAL
crash at COS.
Articles like Mr. Ponder's do little good.
Lots of hand waving and anecdotal
storiesbut little realization that neither the
FAA, the airlines, or the manufacturers
can fix a discrepancy based on stories
about "there I was at 30,000 ft."
The FAA can't mandate a fix for a piece
of equipment until it knows what is the
matter with that equipmentand Boeing
can't fix it until it knows what is wrong.
Sure the FAA is reluctant to ground
2500+ B737s, but the FAA would do it if
they (or Boeing or the NTSB or ALPA or
etc.) could figure out what caused the
The repeated articles and accusations
about all the horrible things the B737 has
done with its rudder don't help
thingsthere needs to be some solid
engineering to actually fix the problem. If
you don't know the cause of a malfunction
and just go mucking around, we are just a
likely to make things worse as fix them.
The recent ADs seem like a resonable
approach to trying to correct some known
problems with the PCU.
I support finding a cause for the PIT and
COS crashes and fixing it. I know the
FAA supports this, and I suspect that
Boeing does also. It would be far better to
swallow this can of worms quickly than to
drag things out. There is no percentage in
a prolonged coverup.
I don't support shooting in the dark,
however, which is apparantly what Mr.
Ponder supports when he advocates his
fix for the B737. What fix? Specifically?
One that will correct a known defect that
can cause an upset of the magnitude that
caused the PIT and COS crashes?
Mr. Ponder, if you have some specifics as
to the exact causes of some of the upsets
you quote, please forward them.
Thousands of hours of engineering has not
been able to duplicate anything that would
cause such an upset.
Like it or not, the engineers are going to
have to fix the rudder problemnot the
Also, pilots seem to get real sensitive
when any insinuations are made about
pilot error. I certainly don't blame the
pilots exclusively for the accidents, but it
seems clear that they had a part in itat
least in the PIT accident. My
understanding was they were pulling 3.8
G's when nearly inverted below 4000 ft.
I can't imagine a situation where this would
be proper response, except maybe in a
Pits Special. Maybe 3.8 negative g's, but
not positive! It seems likely that there was
at least some improper pilot response
(probably in conjunction with other
malfunctions or wake turbulence).
The recent steps by UAL to require their
pilots to undergo unusual attitude training
are very good additions to improve the
airmanship of airline pilots.