Introduction - Section 1 Subject: Model 412 (Description) 1-2 3 View Model 412 1-6 Subject Review 1-8

INTRODUCTION - SECTION 1
TABLE OF CONTENTS
SUBJECT PAGE
MODEL 412 (DESCRIPTION) 1-2
3 VIEW MODEL 412 1-6
SUBJECT REVIEW 1-8

1. MAIN ROTOR HUB AND BLADES
2. TRANSMISSION AND MAST ASSY
3. MAIN DRIVESHAFT ASSY
4. POWERPLANT
INTRODUCTION
The Model 412 EP+helicopter is a twin turbo-shaft engine helicopter, designed for high performance, low maintenance, and maximum versatility. The advanced
design four-bladed rotor system permits a smoother and quieter operation along with the advantage of higher speed.
MAIN ROTOR
The main rotor is a four-bladed, soft in plane, flex-beam yoke type with blade folding capabilities. Elastomeric bearings are used to eliminate conventional
lubrication requirements. The corrosion free fiberglass blades are designed for high aerodynamic efficiency and long component life.
Number of Blades 4
Diameter 46 ft.
Chord (Equivalent) 1 ft. 2 in.
Disc Area 1662 sq. ft.
Airfoil Section 8% at tip 23% at root
Tip Speed 780 ft./sec.
RPM 100% (6600 Eng. RPM) 324 RPM
TRANSMISSION & MAST

The transmission provides a 20.38 to 1 reduction ratio between the powerplant and the main rotor. A secondary drive train which drives the tail rotor and
transmission mounted accessories will continue to operate in the event of an engine failure requiring an autorotation.
TORQUE RATING AS MEASURED AT MAIN ROTOR MAST

Max. Continuous Power 1110 SHP
Takeoff 5 Minute Power 1370 SHP
MAIN DRIVESHAFT
The main drive shaft is connected by splined couplings between an adapter on the engine reduction gear box and the input drive quill on the transmission.
Flexibility of the couplings is provided by a floating-splined method of attachment to the shaft. This method of attachment is used to accommodate movement of the
transmission on pylon mounts. A spring in each coupling assists in centering of the shaft during operation and tends to extend the couplings when the shaft is
removed for maintenance. Shaft couplings are attached to the engine adapter and the transmission input drive quill by bolts.
Main Driveshaft Rotational Speed (100%) 6600 RPM
POWERPLANT
The power plant is a PT6T-9 twinned turboshaft installation, consisting of two identical power sections and a common reduction gearbox. The power sections drive
the output shaft to the transmission through separate reduction gear trains in the combining gearbox.
Model Number PT6T-9

Max. Continuous Power 1650 SHP
Takeoff Power 1855 SHP
Single Engine OEI Power 1100 SHP
Output (100%) 6600 RPM
1. ENGINE AND TRANSMISSION COWLINGS
2. FORWARD FUSELAGE
3. LANDING GEAR
4. TAILBOOM ASSY
5. AERODYNAMIC ELEVATORS
6. ANTI-TORQUE DRIVE SYSTEM
7. TAILROTOR
PYLON FAIRINGS AND ENGINE COWLINGS
The pylon fairing consists of the forward transmission fairing attached to the cabin roof with quick-release fasteners and a two-piece pylon fairing mounted
on the top of the forward fairing and the engine cowling.
The engine cowling consists of several sections, some secured with screws and some fitted with hinges and latches to facilitate maintenance.
FORWARD FUSELAGE
The fuselage consists of two main sections, the forward section and the aft or tailboom section. The cabin has accommodations for 15, including the pilot
and co-pilot in the forward crew compartment and 13 passengers seats in the aft cabin section or passengers/cargo compartment. Conversion from
passenger to cargo configuration is easily accomplished by removal of the seats. Without seats, the cabin affords approximately 220 cubic feet of cargo
space.
LANDING GEAR
The landing gear is a skid-type assembly consisting of two main longitudinal tubes connected by two arched crosstubes. Each longitudinal (skid) tube is
fitted with replaceable wear shoes along the bottom, a towing ring on the forward end, crew boarding step, electrically actuated passenger step, and two
eyebolts for installation of the ground-handling wheels.
TAILBOOM
The tailboom assembly includes the tail rotor driveshaft covers, vertical fin, elevator, baggage compartment, and tail skid. The tailboom assembly is
attached to the forward fuselage section by four high tension bolts.
ELEVATOR
The elevator consists of two separate aerodynamic surface to increase controllability and lengthen center of gravity range.
ANTI-TORQUE SYSTEM
The tail rotor drive system consists of six shafts, one tail rotor drive coupling, four bearing hanger assemblies, and two gear boxes connected in line between
the transmission tail rotor drive quill and the tail rotor.
TAIL ROTOR
A single two-blade controllable pitch tail rotor is located on the right side of the tail rotor gear box. It is composed of two assemblies, the hub and the
blades, and is driven by the tail rotor gear box output shaft. Blades are all metal construction and are attached by bolts to pitch change bearings in the hub
yoke. The tail rotor hub is delta hinge mounted to provide for automatic equalization of thrust on advancing and retreating blades. Control links provide
equal and simultaneous pitch change to both blades. The tail rotor counteracts torque of the main rotor and provides direction heading control.
Number of Blades 2
Diameter 8 ft. 7 in.
Chord 11.5 in.
Disc Area 57.8 sq. ft.
Tip Speed 745 ft./sec.
RPM 100% (6600 Eng. RPM) 1660 RPM
GENERAL DATA MODEL 412
Over-all length (Rotor Turning) 56 ft. 2 in.

Fuselage length (T/R Horizontal)45 ft. 11 in.
Width (Rotor Folded) 9 ft. 4 in.
Height (T/R Horizontal) 11 ft. 5 in.
Landing Gear Tread (No Load) 8 ft. 8 in.
Standard Configuration 6425 lbs
(Approx. Empty Weight)
Maximum Gross Weight 11,900 lbs
Fuel Capacity (Total) 337.5 U.S. Gals.
(Usable) 330.5 U.S. Gals.
Maximum (VNE)140 Kts.
Minimum Temperature -40EC/-40EF
Maximum Temperature +52EC/+125EF
Minimum Starting Temperature -32EC/-25EF
ELECTRICAL POWER SYSTEM
The electrical system is 28 volt D.C. single conductor system with the negative leads connected to the aircraft structure which is used as common ground.
D.C. power is supplied by the generator portion of the two starter-generators operating in parallel feeding the D.C. buses. A 24 volt nickel cadmium battery
can supply selected buses if both generators fail. Two 450 volt-ampere, solid state inverters supply 115/26 volts A.C. single phase, 400 hertz power to the
A.C. buses.
FLIGHT INSTRUMENTS
Standard type flight instruments are installed in the helicopter as basic equipment to comply with the requirements of scheduled air carrier day or night
operations under Visual Flight Rule conditions.
VENTILATION
Cabin ventilation is provided by nose inlet ducts and a single inlet on the roof located under the transmission fairing.
LIGHTING
The helicopter has the required lights installed for VFR night operations, plus additional lighting equipment for utility and convenience purpose.
412 REVIEW
INTRODUCTION
1. The maximum gross weight of the 412EP+ is limited to 11,900pounds on the skids and
11,900 pounds in flight with an external load.
2. The main rotor is described as a soft inplane, - FLEX BEAM

.
3. The main rotor diameter is 46 ft.
4. The 412 consists of two major sections, the forward FUSELAGE

and TAILBOOM
.
5. The 412 can carry two crew members and 13 passengers.

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Introduction - Section 1 Subject: Model 412 (Description) 1-2 3 View Model 412 1-6 Subject Review 1-8

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INTRODUCTION - SECTION 1

MODEL 412 (DESCRIPTION) 1-2

3 VIEW MODEL 412 1-6

SUBJECT REVIEW 1-8

TRANSMISSION & MAST

TORQUE RATING AS MEASURED AT MAIN ROTOR MAST

Model Number PT6T-9

Over-all length (Rotor Turning) 56 ft. 2 in.

2. The main rotor is described as a soft inplane, - FLEX BEAM

3. The main rotor diameter is 46 ft.

4. The 412 consists of two major sections, the forward FUSELAGE

5. The 412 can carry two crew members and 13 passengers.

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