|
| AAIU
Report No:
2001-001 |
|
| AAIU File No:
2000-0009 |
|
| |
|
| Aircraft Type and
Registration: |
Pegasus XL-R, G-MWUE |
| No. and Type of Engines: |
One, Rotax 447 Air Cooled |
| Aircraft Serial Number: |
SW-WA-1513 |
| Year of Manufacture: |
1991 |
| Date and Time (UTC): |
13 February, 2000, 1700 hours |
| Location: |
Baltray Beach, Co. Louth |
| Type of Flight: |
Private |
| Persons on
Board: |
2 |
| Injuries: |
2 Serious |
| Nature of Damage: |
Extensive |
| Commanders Licence: |
UK Private Pilots Licence (Aeroplanes) |
| Commanders Age: |
29 Years |
| Commanders Flying
Experience: |
58 hours |
| Information
Source: |
ATC Watch Manager, Dublin
Airport |
|
Investigation: |
AAIU Field Investigation
|
1. Factual
Information
1.1 History of
the Flight
In an Aircraft Accident Report Form
submitted by the pilot he said that take-off with one passenger
was about 16.30 hours on a lovely sunny Sunday afternoon, with
very little wind from an East North Easterly direction. His
passenger was also the owner of the aircraft.
He flew eastwards towards the coast
from the Drogheda area where he maintained 500-550ft above the
beaches and turned in a southerly direction. On reaching Baltray
Beach the pilot said he noted a slight drop in engine revs so he
descended low over the beach to see if it was suitable for a
landing. However, he noticed deep footprints in the sand and
concluded that the beach was not suitable to land on. Accordingly,
with Baltray Golf Course immediately to his right, he applied full
power to gain altitude and a more promising landing area.
As he approached the mouth of the
River Boyne Estuary the engine suddenly went to idle/tick-over.
There was no response from the foot throttle. Rather than land in
the river or sea the pilot banked the aircraft hard right and
crash landed on the beach, striking it hard on its starboard side.
Some family members, who were close by, witnessed the accident.
They helped the injured pilot and passenger clear of the wreckage
and summoned medical assistance. The pilot and passenger received
serious injuries, necessitating hospitalisation in excess of 48
hours.
In a statement the pilot said that
the low altitude and sudden loss of power rendered his chances of
reaching the relative safety of the nearby golf club impossible.
2. Technical Examination
2.1 Engine Information
A two cylinder, 2-stroke cycle Rotax 447 engine, powers the
Pegasus XL-R. The engine is equipped with one spark plug in each
cylinder. A single magneto assembly powers the spark plugs.
Within this assembly are two coils, each coil provides ignition to
one spark plug.
2.2
Examination of the Engine
The engine was found to be
in good condition and did not appear to have been damaged in the
accident.
However, the earth lead to one of the magneto coils was
found to be broken. The brass connection tab at the end of the
lead was broken. The location of this lead is such that it is
well protected and it is unlikely that the tab was damaged in the
accident or subsequently. The broken connection tab was subjected
to detailed metallurgical examination with the following results.
3. Discussion
Failure of the earth
connection of the magneto coil would result in the sudden and
total failure of the spark to one of the two engine cylinders.
This in turn would lead to a power loss to the propeller exceeding
50%.
Standard aircraft engines feature
two totally separate magneto systems, each with its own spark plug
in each cylinder. This is known as dual ignition. With such a
system, the loss of one complete magneto system, or any component
of that system, results in a relatively minor loss of power,
thereby permitting a safe landing in the event of the failure of
one ignition system. The single ignition system on the Rotax 447
engine has no such safety protection. Therefore such aircraft
should be operated in a manner whereby an engine failure cannot be
considered a remote possibility, but rather as a distinct
probability. Consequently maneuvers such as low runs, which
would require normal engine power to be available for a safe
recovery, should not be attempted in aircraft equipped with such
engines. Such aircraft should be flown in manner that, following
an engine failure at any time, the flight can be safely completed
using a glide (powerless) landing.
Fig 1
The failed magneto lead showing the
separated tab to the left of picture
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