User manual

Part B Section Appendix A.4
A.4 AIRCRAFT OPERATIONS ON THE WATER
01 ENGINE START AND RUN UP
The starting of the engines on the water produces movement of the aircraft. There are no
brakes to hold the aircraft during start, engine warm up, run-up and pre-take off checks.
The aircraft must be clear of buoys, markers, moorings and of other marine craft before
starting engines.
From a mooring it is often best to pay out line from the bow while still secured by a bow
line fixed to the mooring using a slippery hitch. Similarly, from anchor, out more line then
start and taxi back up to the anchor position while the anchor is hauled in. Should there be
a problem getting the engines started it is easier pull back up to the mooring or anchor
position rather than be forced to re-anchor or have the aircraft drift.
The starting sequence is the same as for operations on land but to have the aircraft quickly
under control a prompt start is preferred. This will minimise the turning of the aircraft on
asymmetric power. Combining power and sailing techniques, clear the mooring area and
allow the engines to warm up. Gentle circular turn patterns can minimise the water area
required.
Once clear of all obstructions the engines can be run up using the Standard up checklist.
The engines can be run up one at a time allowing the aircraft to steadily in circles first one
way then the other. Alternatively the 1700RPM checks can be done for both engines at the
same time so long as the non-flying pilot keeps the control yoke fully back and a good
lookout is maintained by all crewmembers.
02 TAXIING
Low Speed (Displacement) Taxi: Considerable practice is necessary for successful water
taxiing. There are no water rudders to aid in directional control. Differential power, rudder
deflection (towards desired turn), aileron drag (turn away from turn direction), lowering
undercarriage and using drogues are all of value in handling the aircraft on the water. The
engines are close to the centreline and differential power is there less sensitive than would
be ideal so the other methods must be used in confined areas, such as when close to
docks and beaches or among boats, they moored or under way.
Into wind taxiing
is the easiest direction to master. With a wind speed of 10-12 knots the aircraft can come
to a stop with engines idling. With a good airflow over the wings the ailerons can be used
to help keep a chosen wingtip float in the water providing water drag and improving turning
ability. This is a more powerful way of controlling a turn than relying on aerodynamic drag
from the "down" aileron (sailing) but requires a wind of about 10 knots to become effective.
Cross wind taxiing
is more difficult because of the strong weather-cocking tendency of the Catalina. A higher
power setting on the up-wind engine is necessary and results in a higher taxi speed. As
wind speed increases the cross wind taxi ability decreases and in strong winds the pilots
must power taxi as far across the wind as can be achieved then shut down engines and
tack the aircraft in "sailing" mode before restarting the engines, so zigzagging in the
desired direction. A drogue streamed from the leeward side of the aircraft allows cross
wind taxiing in stronger wind conditions and the drag provided usually means 1000RPM
can be maintained on the leeward engine with higher power on the windward engine. Plug
fouling on the leeward engine is then less likely but overheating of the windward engine is
still a risk.
Stichting Catalina PH-PBY Rev No: 02
01 April, 2006 Page: 1