Each model of Sky-Tec starter may
or may not ship with a jumper wire between the S-Terminal and
the Power Terminal of the starter. Here's a guide
intended to help keep the variations straight.
Why a jumper wire?
Sky-Tec starters feature an
integrated solenoid that is primarily used to physically push
the drive gear forward into the ring gear.
Alternatively, in some applications, this solenoid may be
wired to serve a dual purpose by also serving as the
aircraft's main starter contactor (starter
Let us first look at an
installation where the airframe is configured with a separate
firewall starter solenoid or "starter
Here at Sky-Tec, we tend to
refer to this type of installation as a "Certified
Aircraft" installation because the vast majority of
certified aircraft were certified with a starter contactor
installed on the firewall (or similar location).
However, we realize there are some certified aircraft that
were certified to use the starter's integrated starter
contactor (Robinson Helicopters, for instance). So while
we delineate "Certified Aircraft" wiring from
"Experimental Aircraft" wiring in this way, the
definitions are not foolproof.
HOWEVER, please note, if your
aircraft was certified for use with a separate firewall
starter contactor, you MUST continue to use that contactor and
wire your starter according to the "Certified
Aircraft" wiring diagram below.
Robinson Helicopter's will be
wired according to the "Experimental Aircraft"
wiring diagram below (even though they are certified
And finally, experimental
aircraft may be wired either way at the builder/owner's
NOTE REGARDING 12V/24V SWITCHABLE (STANDARD) NL MODEL STARTERS
Sky-Tec repurposed the S-Terminal
functionality on NL model starters to serve as a means of
switching the starter between 12V and 24V operation.
Because of this, ALL NL STARTER
INSTALLATIONS MUST BE WIRED ACCORDING TO THE CERTIFIED
AIRCRAFT WIRING DIAGRAM BELOW - NO EXCEPTIONS!
NOTE REGARDING NL/ec* *24V SuperDuty MODEL STARTERS
Unlike the standard 12V/24V
Switchable NL starter (above), the S-Terminal
functionality is fully functional on NL/ec* *24V SuperDuty starters.
For any application using a separate starter contactor
(starter relay), leave the jumper wire in place. For 24V
Robinson Helicopters or any experimental application desiring
to use the starter's internal solenoid as the starter
contactor, remove the jumper and bring bus power through the
push-to-start switch to the smaller, S-Terminal to activate
NOTE REGARDING START SWITCHES
Because Sky-Tec starters use
their integrated solenoid to serve a MECHANICAL purpose
(pushing the drive gear forward into the ring gear), switch
connections to the S-Terminal must be capable of handling up
to 30 Amps (30 Amps peak - 6 Amps nominal). Therefore,
it is imperative that IF YOU INTEND
TO USE A RIGHT-LEFT-BOTH-START-TYPE KEY SWITCH, YOU MUST
WIRE YOUR AIRCRAFT USING THE CERTIFIED AIRCRAFT WIRING DIAGRAM.
We are unaware of any key switches available on the market
today that can safely carry the requisite 30 Amp peak load.
NOTE REGARDING HT MODEL STARTERS
HT model starters manufactured
before 2006 featured an INTERNALLY jumped solenoid. We
figured there were very few, if any, experimental aircraft
flying with 24V electrical systems so we hard wired the
starters internally for certified 24V applications.
Well, Robinson Helicopter and an increasing number of
experimental aircraft with 24V electrical systems persuaded us
to move the jumper wire to the outside of the solenoid HT
model starters just like it has always been on 12V models so
that it may now be installed in either Certified or