Francis gave me permission to put this letter (which he has already sent to
"flying Europas)on to the net. Hope you find it useful. RonS No33
From: Francis Donaldson
Dated: 6th October 1998
VARIABLE PITCH PROPELLERS
It has come to our attention that the manufacturers of Arplast and NSI
controllable-pitch propellers do not provide comprehensive instructions
regarding the techniques for the operation of aircraft with their propellers
fitted. The Europa flight manual only deals with the use of ground-adjustable
propellers. Techniques differ from those of more common 'constant speed'
propellers.
This being the case the PFA National Coach, John Brownlow, has written up
additional aircraft handling notes covering the operation of the NSI propeller
fitted to the Rotax 912 powered Europa based on his flying in G-BWZT. I am
enclosing a copy of these notes for your use/interest.
Obviously the techniques and rpm figures will differ slightly when using the
NSI propeller fitted to the NSI Subaru engine or when using the Arplast
propeller fitted to the Rotax 912, but the fundamental ideas will still be
applicable.
The main risk with these propellers is that if care is not taken, the engine
max rpm will be exceeded if the airspeed is allowed to increase whilst fine
pitch and full throttle are selected. Some Europa owners have chosen to set up
their propellers with the fine pitch stop very fine, so as to allow peak power
to be developed at the start of the take-off run. This results in additional
pilot workload during the initial part of the climb because the pilot must
remember to either maintain the airspeed not above 60 knots or to coarsen the
prop pitch.
Europa Aviation and the PFA recommend that the propeller fine pitch stop be
set up so that when climbing out at full throttle, the maximum permitted
engine rpm is not exceeded unless the airspeed exceeds 80 Knots. This results
in a very slight take-off performance penalty but greatly reduces the risk of
inadvertent engine overspeeding and reduces pilot workload during the critical
climb-out phase. In making this recommendation we are particularly mindful of
the several accidents which have befallen Europa pilots during the climb-out
phase and the need to concentrate on flying the aeroplane when so close to the
ground, rather than having attention diverted to propeller pitch switch, prop
pitch indicator and tachometer.
PFA inspector John Scott of Cambridge has experienced difficulty with NSI
propellers when using a 12 volt power supply to motor the propeller pitch
change directly during setting-up. With the motor running off a 12 volt
supply, the force generated by the lead screw is apparently sufficient to
damage the hub, dragging the lead screw bearing partially out of its housing
and causing erratic propeller pitch stop settings. John suggests owners should
take care to either motor the propeller from the NSI control unit, which cuts
down the voltage, or if using a battery directly, use a 6 volt rather than 12
volt battery.
Tony Wakefield found that when he fitted a VP prop to his Europa an unwelcome
side-effect was that due to the engine now being able to operate at peak power
in a prolonged climb, the extra heat generated by the engine and exhaust
triggering a problem with charring of an oil cooler pipe - see below. Always
be wary of unforeseen 'knock-on' effects !
TACHOMETER CALIBRATION
It has also been pointed out that some Rotax installations have suffered from
significant instrument errors on the tachometers used and this has given rise
to misleading rpm indications, in one case by as much as 400 rpm. This could
lead to propellers being wrongly pitched and engines either failing to achieve
peak power, or being damaged through excessive rpm. To avoid this the
tachometer should be calibrated using an optical type strobe, and adjusted for
minimum error. The tacho supplied by Europa has an adjustment screw for this
purpose. Euroa Aviation are investigating means of supplying tachometers pre-
calibrated in future.
EXHAUST SYSTEM CRACKING
We have recently seen a forced landing on Bob Gibbs' Europa G-IBBS
(fortunately without damage) due to failure of one of the exhaust downpipes on
its Rotax engine, causing hot exhaust gas to play on the adjacent carburettor.
A similar exhaust system failure and forced landing occurred on Bill Williams-
Wynne's Subaru powered Europa some time back. Please take care to inspect
exhaust systems carefully for signs of cracking and blow-by during regular
'first flight of the day'checks even if it means removing and replacing the
many screws used to hold your cowling in place. Only by constant vigilance can
such unpleasant surprises be avoided. Use of insulating wrap around exhaust
pipes can help reduce under-cowl temperatures but in doing so it can greatly
increase the exhaust pipe temperature promoting rapid corrosion and cracking,
whilst hiding the affected area and preventing cracks being seen before they
become catastrophic. Use of insulating wrapping should therefore be avoided.
Europa Aviation are in the process of issuing Service Bulletin number 3 on the
subject.
COCKPIT ERGONOMICS
The accident which wrote-off the brand new Europa G-MAVE during its test
flying phase occurred because the NSI Subaru engine, having stopped for some
reason as yet undetermined but possibly related to the fuel supply, did not
re-start in the few seconds available before the pilot had to focus his
attention on the forced landing. The pilot commented that his efforts to re-
start were hampered by the location of the fuel primer at the opposite side of
the instrument panel from the starter switch, making it impossible to operate
both simultaneously with one hand. Please consider the ergonomics of your
controls carefully and put right any such 'gotchas' before they have a chance
to bite.
Possibly contributing to this accident, the empty weight of
G-MAVE at 924 Lbs was almost 200 Lbs more than that of the lightest Europa yet
built. Consequently the aeroplane had a greatly reduced payload and could only
carry minimal fuel when flown two-up. As we have stressed many times, it is
all too easy to increase the weight of an aircraft, but at the end of the day
an aeroplane with a complex instrument and avionics fit is of very little use
if it can't haul a sensible load.
OIL PIPES
Several owners of Rotax powered Europas have had trouble with the rubber oil
pipes deteriorating due to charring at the point where they pass close to the
exhaust system. Please take note of the Europa modification no. 48 just issued
on the subject and action accordingly before next flight. Failure of the pipe
could quickly lead to loss of engine oil and destruction of engine.
FUEL FILTERS
Experience has shown that the fuel filter supplied in the kit can be blocked
by a relatively small amount of contaminant in the fuel, leading to engine
power loss in flight. Particular care must be taken to avoid polythene swarf
being left in the tank
especially if the tank is re-worked to accept fuel quantity senders or
similar. PFA have approved a modification on Europa G-EMIN which replaces the
existing single filter with two similar filters, one in each of the fuel tank
outlet pipes, upstream of the fuel selector valve. With the modified system,
if fuel starvation is experienced due to the main filter blocking, when the
pilot selects 'reserve tank' the fuel can flow to the engine via the
alternative filter. Europa Aviation are in the process of issuing Mod 49 on
this subject, recommending an essentially identical modification.
MAX GROSS WEIGHT
It now seems that Europa Aviation are concentrating on the 'XS' model and do
not intend to carry out the load tests required to prove that standard-winged
Europa is eligible for a max gross weight increase from 1300 to 1370 Lbs. This
makes it all the more important to keep the empty weight of the aircraft low
so as to provide adequate payload at 1300 Lbs. The empty weight of Europas has
varied from 730 Lbs to 924 Lbs, and it should be obvious that with an empty
weight above 850 Lbs the usefulness of the aeroplane is severely restricted,
as it is no longer possible to load two average size adults and full fuel,
even without baggage.
VNE
Please note that despite what figures you may see elsewhere, the Vne for the
standard Europa as cleared by the PFA is that stated on the Permit to Fly, 150
knots. We continue to receive flight test results from owners quoting the
aeroplane as having been flown to 165 knots. The design submission for the
standard Europa has been based around a 150 knot Vne and PFA has not cleared
the aircraft for flight at higher speeds. Whilst the prototype flight testing
has proven the aeroplane to be flutter-free at 10% higher airspeeds, so as to
ensure an adequate margin of safety, there is no guarantee that a homebuilt
will exactly replicate the characteristics of a prototype. Owners must check
that their cockpit placards and airspeed indicator 'red lines' reflect the 150
mph Vne and observe this limit in flight.
ROTAX 912S ENGINE
The PFA has now cleared the 912S engine following a successful 25 hour flight
test period in an ARV Super Two belonging to Nigel Beale of Skydrive. This
engine seems a natural for the Europa, and Europa Aviation are at present
installing one in their tri-gear prototype G-KITS in place of the Mid-West
rotary previously installed, at the same time uprating the aeroplane to 'XS'
specification.
It remains to be seen how straight-forward it is to retro-fit a 912S to an
existing Europa. Additional cooling provisions are bound to be required,
current plans being for an extra oil cooler mounted under the propeller shaft.
Francis Donaldson
Chief Engineer
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