January 1, 2001
Buying
with Bower: FADEC And Your Helicopter, Part 2
by Ron Bower
ENGINE MANUFACTURERS ALL seem to agree that a faster turbine engine start
with stabilized temperature will save you big bucks in repairs and overhauls,
and also will reduce stress on starters and batteries.
Ultimately, the goal is longer overhaul intervals for engines with FADEC.
All of the benefits will reduce engine direct operating costs (DOCs) and should enhance safety.
A new STC’d product from Honeywell/Altair is Intellistart Plus+. This system performs FADEC-like autostart and full HUMS monitoring for the Rolls-Royce
Model 250-C20 and -C30 families of engines found on thousands of
Last year, AlliedSignal bought Honeywell and took the Honeywell moniker.
Before the purchase, AlliedSignal bought Bendix
(manufacturer of the Bendix fuel controls and
governors in most Rolls-Royce Model 250 engines), so Honeywell is now the
keeper of the knowledge and data about fuel controls and governors for older
non-FADEC engines.
These Bendix fuel controls and governors have tens
of millions of proven flight hours and very rarely show signs of problems. With
the Honeywell Intellistart Plus+, no changes in pilot
procedures are required for starting or in flight operation. Intellistart Plus+ stops controlling the fuel flow as soon
as the start cycle has ended (60% of N1 RPM). Only the HUMS portion stays alive
to perform passive monitoring. As a result, there are no new emergency
procedures to master.
I recently performed multiple, quick-succession
starts on a Rolls-Royce Model 250-C28 in a Bell LongRanger
II equipped with Honeywell’s Intellistart Plus+
system.
Although I never had a hot start in my several thousand hours in turbine
helicopters, Intellistart Plus+ convinced me that I
had few optimum starts. I did five starts, four of them with the rotors still
turning from the previous shutdown.
On all five starts, the TOT climbed quickly to a preprogrammed 783°C (10°C
below the 793° mark that begins a 10-second limit) and stabilized right there,
plus or minus 2°C, for the duration of the start cycle. The procedure did not
require throttle modulation.
On some of the starts, just after ignition at 14% of N1 (or a little higher,
if needed to get the residual TOT down to 150°C, according to the flight
manual), I immediately rolled the throttle to the flight idle detent using the
same technique for starting a JetRanger equipped with
the -C20B engine.
Instead of hot starting, the system consistently performed 17-second starts
with the TOT pegged at 783°C—far better for the engine than I could ever do
with manual modulation.
Try it yourself. The next time you start, see how long the start is and whether
the TOT is stabilized or jumps all over the gauge as the mechanical fuel
control schedules the fuel into the engine. Older fuel controls do not have any
TOT information for their fuel scheduling decisions.
With Intellistart Plus+ or FADEC, a hot start
should be a thing of the past. You can still do it if you don’t follow the
simple procedures, but it is almost foolproof.
Another benefit of most standard FADECs and Intellistart Plus+ is that they can produce an accurate
accounting of flights, starts, torque events, exceedences,
and power checks.
Ultimately, this information, if properly recorded, will become a value item
when aircraft are bought or sold. Wouldn’t you feel better buying a used
helicopter that had accurate records of not just how long it was flown, but how
it was flown? Since the engine is by far the most expensive single component on
rotorcraft, protecting this valuable asset is crucial to preserving a
helicopter’s total value.
The objective HUMS system data also will enable operators to trend the
health of their fleets’ engines. The life-saving benefit of HUMS is early
detection of potential problems and taking corrective action before the problem
becomes serious.
Because the FADEC or HUMS systems are dynamically monitoring the inputs at
computer speeds, pilots will begin to see more flight management information in
the cockpit. A good example is the FADEC-controlled
It doesn’t take any training to understand this helpful information; you
don’t have to look at a gauge, you just intuitively lower the collective until
the vibration stops, maintaining maximum power and avoiding an overtorque.
Eventually, FADECs and HUMS will be in most helicopters.
In some cases, such as