- Serling, Robert J.
The Electra Story.
New York: Bantam Books, [1963] 1991.
ISBN 978-0-553-28845-2.
-
As the jet age dawned for commercial air transport, the
major U.S. aircraft manufacturers found themselves playing
catch-up to the British, who had put the first pure jet
airliner, the
De Havilland Comet, into service in 1952,
followed shortly thereafter by the turboprop
Vickers Viscount in 1953. The Comet's
reputation was seriously damaged by a series of crashes
caused by metal fatigue provoked by its pressurisation system,
and while this was remedied in subsequent models, the
opportunity to scoop the Americans and set the standard for
passenger jet transportation was lost. The Viscount was
very successful with a total of 445 built. In fact, demand
so surpassed its manufacturer's production rate that delivery
time stretched out, causing airlines to seek alternatives.
All of this created a golden opportunity for the U.S. airframers.
Boeing and Douglas opted for four engine turbojet designs, the
Boeing 707 and Douglas DC-8, which were superficially similar,
entering service in 1958 and 1959 respectively. Lockheed opted
for a different approach. Based upon its earlier experience
designing the
C-130
Hercules military transport for the U.S. Air Force, Lockheed
decided to build a turboprop airliner instead of a pure jet
design like the 707 or DC-8. There were a number of reasons
motivating this choice. First of all, Lockheed could use
essentially the same engines in the airliner as in the
C-130, eliminating the risks of mating a new engine to a new
airframe which have caused major troubles throughout the
history of aviation. Second, a turboprop, although not as fast
as a pure jet, is still much faster than a piston engined plane
and able to fly above most of the weather. Turboprops are
far more fuel efficient than the turbojet engines used by
Boeing and Douglas, and can operate from short runways
and under high altitude and hot weather conditions which
ground the pure jets. All of these properties made a turboprop
airliner ideal for short- and medium-range operations where
speed en route was less important than the ability to operate
from smaller airports. (Indeed, more than half a century
later, turboprops account for a substantial portion of the
regional air transport market for precisely these reasons.)
The result was the Lockheed L-188 Electra, a four engine
airliner powered by Allison 501-D13 turboprop engines,
able to carry 98 passengers a range of 3450 to 4455 km
(depending on payload mass) at a cruise speed of 600 km/h.
(By comparison, the Boeing 707 carried 174 passengers
in a single class configuration a range of 6700 km at
a cruise speed of 977 km/h.)
A number of U.S. airlines saw the Electra as an attractive
addition to their fleet, with major orders from American
Airlines, Eastern Air Lines, Braniff Airways, National
Airlines, and Pacific Southwest Airlines. A number of
overseas airlines placed orders for the plane. The entry
into service went smoothly, and both crews and passengers
were satisfied with the high speed, quiet, low-vibration, and
reliable operation of the turboprop airliner.
Everything changed on the night of September 29th, 1959.
Braniff
Airways flight 542,
an Electra bound for Dallas
and then on to Washington, D.C. and New York,
disintegrated in the skies above Buffalo, Texas. There were no
survivors. The accident investigation quickly determined that
the left wing of the airplane had separated near the wing root.
But how, why? The Electra had been subjected to one of the
most rigorous flight test and certification regimes of its
era, and no problems had been discovered. The flight was
through clear skies with no violent weather. Clearly, something
terrible went wrong, but there was little evidence to
suggest a probable cause. One always suspects a bomb (although
less in those days before millions of medieval savages were
admitted to civilised countries as “refugees”), but
that was quickly ruled out due to the absence of explosive residues
on the wreckage.
This was before the era of flight data recorders and cockpit
voice recorders, so all the investigators had to go on was
the wreckage, and intense scrutiny of it failed to yield an
obvious clue. Often in engineering, there are mysteries which
simply require more data, and meanwhile the Electras continued
to fly. Most people deemed it “just one of those
things”—airliner crashes were not infrequent in
the era.
Then, on March 17th, 1960, in clear skies above Tell City, Indiana,
Northwest
Airlines flight 710 fell out of the sky, making a crater in
a soybean field in which almost nothing was recognisable. Investigators
quickly determined that the right wing had separated in flight, dooming
the aircraft.
Wings are not supposed to fall off of airliners. Once is chance, but
twice is indicative of a serious design or operational problem.
This set into motion one of the first large-scale investigations of
aircraft accidents in the modern era. Not only did federal investigators
and research laboratories and Lockheed invest massive resources, even
competitors Boeing and Douglas contributed expertise and diagnostic
hardware because they realised that the public perception of the safety
of passenger jet aviation was at stake.
After an extensive and protracted investigation, it was concluded that
the Electra was vulnerable to a “whirl mode” failure, where
oscillations due to a weakness in the mounting of the outboard
engines could resonate with a mode of the wing and lead to failure
of its attachment point to the fuselage. This conclusion was
highly controversial: Lockheed pointed out that no such problem
had been experienced in the C-130, while Allison, the engine
manufacturer, cited the same experience to argue that Lockheed's
wing design was deficient. Lawsuits and counter-suits erupted, amid
an avalanche of lawsuits against Lockheed, Allison, and the airlines
by families of those killed in the accidents.
The engine mountings and wings were strengthened, and the modified
aircraft were put through a grueling series of tests intended
to induce the whirl mode failures. They passed without
incident, and the Electra was returned to service without any
placard limitations on speed. No further incidents occurred,
although a number of Electras were lost in accidents which had
nothing to do with the design, but causes all too common in
commercial aviation at the time.
Even before the Tell City crash, Lockheed had decided to close
down the Electra production line. Passenger and airline preference
had gone in favour of pure jet airliners (in an age of cheap oil,
the substantial fuel economy of turboprops counted less than
the speed of pure jets and how cool it was to fly without
propellers). A total of 170 Electras were sold. Remarkably,
almost a dozen remain in service today, mostly as firefighting water
bombers. A derivative, the
P-3 Orion
marine patrol aircraft, remains in service today with a total of
757 produced.
This is an excellent contemporary view of the history of a
controversial airliner and of one of the first in-depth
investigations of accidents under ambiguous circumstances
and intense media and political pressure. The author, an
aviation journalist, is the brother of
Rod Serling.
The paperback is currently out of print but used copies are
available, albeit expensive. The Kindle
edition is available, and is free for Kindle Unlimited
subscribers. The Kindle edition was obviously scanned from
a print edition, and exhibits the errors you expect in scanned
text not sufficiently scrutinised by a copy editor, for example
“modem” where “modern” appeared in
the print edition.
December 2017 