Recent
Incidents & Blasts from the Past
Your editors decided to escape from
wet and windy Wales in August but we are back in harness and have back-filled
the August slot with six brief articles. The first two are based on very
recent incidents, the remaining four, though less recent, still carry
salutary lessons.
Stow It!
A recent
accident to a light aircraft occurred because the control stick became jammed
by the pilot’s kneeboard mounted on his thigh. The pilot pulled back
hard to free the restriction, then the stick moved rapidly to apply full up
elevator. The aircraft stalled into the ground causing considerable damage to
the airframe, engine and propeller.
A CAA General Aviation Safety Information Leaflet (GASIL) issued in
September 2003 recommends that while kneeboards are useful during cruise they
should be placed in a safe, secure place during critical phases of flight
such as takeoff and landing.
Now you know why.
How Long May You Leave Your Parked
Aircraft?
Many GA
aircraft are either parked on the airfield or stored in a hangar for several
weeks without use, particularly during winter months. Did you know that CAP
411, the Light Aircraft Maintenance Schedule (LAMS) or its replacement CAP
766, the Light Aircraft Maintenance Programme (LAMP) specify a MAXIMUM period
between engine runs? Both documents require piston engines to be either run
EVERY 14 DAYS or turned over by hand EVERY 7 DAYS.
I suspect that this regulation is not observed by all GA aircraft
owners. Does it matter? Well, yes it does. A recent fatal accident involving
a PA23 Aztec when both engines produced only reduced power and the pilot spun
off an attempted turn back after takeoff was probably caused by failure to
observe the above requirement. The aircraft had spent long periods stored in
the open over the previous 5 years. The fuel systems of both engines were
corroded causing restricted flow through the injectors. The injectors had
required cleaning prior to the fatal accident flight and both engines
appeared to run satisfactorily on the ground. However, after takeoff both
engines produced visible smoke and the aircraft seemed to have a much reduced
rate of climb. It climbed slowly at low speed, producing smoke from both engines.
The aircraft turned steeply towards the runway reciprocal, the left wing
dropped suddenly and the aircraft pitched down, hit the ground and burst into
flames.
Ignoring the errors in technique by the pilot after suffering
incipient engine failure, the root cause of this accident was the problem
with the engines.
I have been flying for over 55 years but was not aware of the
REQUIREMENT to either run the engine every 14 days or to turn it by hand
every 7 days until I read about it in a recent issue of the CAA General
Aviation Safety Information Leaflet (GASIL). Does everyone else know about
this requirement? Does everyone observe it? How about your Gliding Club tug
aircraft? Who takes care of the Group aircraft? Have you ever left your
aircraft unattended for more than 14 days?
Lost Electrics
A Beechcraft F33 Bonanza with two pilots on board was
flying from Blackbushe Airport to Bournemouth and was in contact with
Farnborough Radar when the aircraft had a total electrical failure.
The aircraft turned right onto a northerly heading to
avoid controlled airspace and the systems were checked. Blackbushe was
contacted by mobile phone and advised that the pilot intended to continue
north to Wellesbourne Mountford, an airport with which he was familiar. The
weather deteriorated in rain and visibility below VFR limits. Abingdon
Airport was visually identified and Farnborough ATC was contacted by mobile
phone to advise them of the intention to land there. The landing gear was
lowered manually but, being unable to check that the gear was fully down, the
pilot decided to perform an engine off landing. The engine was shut down and
the fuel selected off over the runway threshold. The aircraft landed very
gently but the gear collapsed while the aircraft came to rest on the runway
centreline. There was no fuel spillage and no injury to the occupants.
The engineering organisation
that recovered the aircraft from Abingdon reported that the aircraft’s
electrical system, normal electrical landing gear system and manual gear
extension system all operated normally prior to aircraft recovery so no technical
reason for this accident was found.
The value of carrying a mobile phone in the air with a Flight
Guide listing airfields, facilities and their telephone numbers was proved in
this case.
This report is closely based on AAIB Report
ew/G2004/10/08, which source is gratefully acknowledged.
Don’t Assume — Check!
How often during training are we reminded that
‘Vital Actions’ are VITAL?
An experienced professional pilot flew his
Piper PA-34 Seneca II to Stapleford airfield early in the morning to have the
autopilot repaired. The repair was completed and the engineers told the pilot
that only the autopilot computer had been removed to complete the repair. The
pilot lined up for departure on Runway 22 which is asphalt for the first 600
metres and grass for the remaining 477 metres. There was a 15 kt crosswind
from the right. The pilot found he was ‘fighting to keep the nose up’
as the aircraft left the ground. He tried to use the electric elevator trim
but found it did not work. He abandoned the takeoff and landed heavily on the
remaining grass runway. The left propeller touched the ground before the
aircraft was brought to a halt.
Examination showed the elevator trim in the fully nose-down position
and that the circuit breaker for the electric trim had been pulled. The pilot
candidly admitted that he had not checked the trim prior to departure because
he assumed it had been undisturbed during the repair to the autopilot. He
accepts he should have checked the trim and believes the engineers should
have pointed out that the circuit breaker had been pulled and they should
have returned the elevator trim to the take-off position when they completed
the autopilot repair.
Checks and vital actions by the pilot are fundamental to the safe
operation of an aircraft. There can be no justification for taking short cuts
or making assumptions. This accident also highlights the importance of
accurately documenting all work that has been done on an aircraft, especially
when it has implications for operational safety.
(Based on AAIB Report EW/G2004/08/13 which source is gratefully
acknowledged).
Hours Alone Are Not Enough #1
Over the years there have been a number of
accidents and incidents involving GA aircraft where the pilot has held a
professional licence and has thousands of hours on ‘heavy metal’
but few (recent) hours on light aircraft.
A pilot holding an ATPL with 7,500 hours
experience but with only 10 hours on type was travelling at low speed after
landing his Pitts S-1C aerobatic biplane in benign weather when the aircraft
suddenly ground-looped violently to the right. The lower left wing and the
propeller struck the ground and the aircraft pitched rapidly over its nose
before coming to rest inverted. The pilot was able to climb out of the
wreckage uninjured. His five-point harness and crash helmet protected him
from injury.
The Pitts is a short-coupled aircraft that demands constant and
immediate control input while taxiing in any condition. It is all too easy to
relax at the end of a landing run. Student pilots on Harvards in the 1950s
were given some very good advice that may be applied to any aircraft.
“Remember, the landing is not complete until the wheels
have stopped turning.”
Hours Alone Are Not Enough #2
Another pilot holding an ATPL with over 4,000
hours experience but with only 10 hours on type was taking off from a grass
strip in his Boeing A75N1 Stearman biplane powered by a 220hp Continental
radial engine. The air temperature was +10C above standard and the aircraft
was about 200 lb below its maximum authorised take-off weight. The aircraft
left the ground in a ‘three-point’ attitude and did not
accelerate. The Stearman reached a maximum altitude of about 100 feet agl
during this attempted takeoff. Witnesses recalled the aircraft appearing to
be flying close to the stall, with a series of wing drops before it descended
into a field beyond the airfield boundary with the engine apparently
producing full power until impact. The aircraft suffered severe damage on
impact and caught fire after turning over onto its back. The pilot and
passenger were able to escape without assistance, although the pilot was
injured.
The following comments are those of the Gremline editor and
do not profess to reflect the views of AAIB.
My own experience on this version of the Stearman is limited to a few hours
on the PT17A, with most of my time on the much more powerful version with the
450 hp Pratt & Whitney R985 engine.
This pilot had very limited experience on the Stearman. From the
evidence provided by four witnesses, including at least one experienced
pilot, it appears that the aircraft left the ground in a nose high attitude,
did not accelerate and appeared to climb to about 100 feet agl while
remaining close to stalling speed before descending to impact. In my opinion,
this is a classic description of an aircraft of limited performance climbing
out of ground effect whereupon the large increase in lift induced drag
overcame the small margin of excess power available and caused the aircraft
to stall and descend into the ground. Had the aircraft achieved a lower nose
attitude (higher tail attitude) before leaving the ground it is more likely
that it would have accelerated to a speed sufficient to allow it to climb
away in safety. Had the pilot lowered the nose as far as possible once he
recognised the lack of acceleration then it is possible that the Stearman
would have accelerated sufficiently to climb away. This opinion is not meant
to be a criticism of the pilot who lacked experience on type, but is intended
to bring to the attention of all pilots the relationship between ground
effect and lift induced drag, and particularly to those pilots who operate
light aircraft with limited excess performance from runways of limited
length.
There is a full explanation of the relationship between lift induced
drag and ground effect in our October 2007 article
Accidents on Takeoff.
(Based on AAIB Reports EW/G2004/07/08 and EW/G2004/08/01 which
sources are gratefully acknowledged).
Text and Photographs © 2008 Gremline & Hill House
Publications, unless otherwise stated.
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