|
BASIC ENGINEERING CHANGES TO DHC-4 CARIBOU Engine mounting · Utilize existing
nacelle mounting hard points and two additional hard points totaling six. · Engine mounting
structure design to failsafe criteria. · Inclusion of
vibration isolator, four each per engine. · Provide ease of access
for servicing. Four large engine nacelle accesses, two swinging doors (also
removable), two large removable panels. · Quick engine change (QEC) capability. QEC
can be performed without removing top cowling. Left/right interchangeable. Exhaust System · Enclosed exhaust
system with dual augmentation design is also used to induce nacelle
ventilation and reduce IR signature. Air intake: Aircraft System Changes
Changes
were made only to those systems that were incompatible with the change of
power plant. These are summarized as follows: · The aircraft fuel system is the same
design except for additional boost pump, new type fuel filters and a fuel totalizer
system. · The DC electrical system changes to
generators and starter motors required to suit the turbine engines. · Cockpit instrumentation was changed to
state of the art "EMIS" engine monitoring system. · Engine control system modified for PT6-67T
engine needs utilizing 'ball bearing' type cable throughout the system. · Original hydraulic pumps driven
electrically. · Power plant fire selection changed to
single zone dual loop. Engine and Propeller ControlsWith a revised engine and propeller the
Turbo Caribou has had the controls modified, but still keeping the overhead
console between the pilot and co-pilot. The existing rope type engine control
cable system has been replaced with ball bearing type cable system throughout
the airframe and nacelle run. Redesigned for PT6-67T use are as follows: Hydraulic System
Hydraulic system balance maintained by utilizing existing pumps and driven electrically through auto logic which allows deactivation of system when not required during flight. |
Fire Detection
System The Turbo Caribou fire detection system uses a single zone dual loop type. Its purpose is to prevent any false indications and offer redundancy in case of the two loops fail. Pneumatics Electrical SystemThe fitting of a combined DC starting generating unit to the engine gearbox for the re-engined Caribou offers the simplest and the most cost effective means of incorporating these functions. The control and protection circuitry is based on the existing control panel which has been retained as far as practicable. Also updated are dual transverters (inverters) and new dual generator control units (GCU) which incorporate a self paralleling feature. To provide a positive and efficient starting capability a second lead acid battery is provided, which is paralleled to the existing lead acid battery system. Engine Instrumentation 'EMIS'The existing center panel in the cockpit engine instrument display was changed to suit the new power plants. Modern state of the art instrumentation has been incorporated using 'EMIS' digital/analog integrated instrument system with engine monitoring and exceedence recorder and fuel computer, and interface to download data. Fuel Management · Manual fuel loading · Fuel remaining display · Fuel used display · Flight hours remaining display Exceedence Monitoring
· Records peak value, average value and
duration when any instrument exceeds a (software) present limit. · Exceedence alarms Engine Instrumentation 'CHECKPOINT'Optionally, a Horizon Aerospace digital/analog
instrument system can be installed. The advantage of this system is in
addition to replicating the functions of the 'EMIS' system, the Horizon
'CHECKPOINT' system analog gauges can be repalced individually and the system
digital display (DDMP) also monitors the aircraft electrical system. |