Mauna Loa Helicopters - VFR Ground School Lesson 1: Helicopter Systems and SFAR 73

Comprehensive review flashcards covering Lesson 1 of the Mauna Loa Helicopters VFR syllabus, including airframe construction, rotor systems, Lycoming powerplant, transmission, oil and fuel systems, flight controls, electrical system, instruments, magnetic compass errors, and SFAR 73 awareness training.

What primary materials make up the airframe structure of the Robinson R22/R44?

The primary fuselage structure is made of welded steel tubing and riveted aluminum panels, with fiberglass thermoplastic used for non-structural secondary components.

What type of structure is the tail cone of the R22, as shown from the inside?

An aluminum monocoque structure in which the skin carries the primary load.

What structural role does the vertical stabilizer serve in forward flight?

It improves aircraft stability and reduces the required thrust from the tail rotor by acting as an airfoil that produces aerodynamic force in the same direction as tail rotor thrust.

What are the two primary purposes of the horizontal stabilizer?

It helps level the fuselage in forward flight and provides additional clearance between the main rotor blades and the tail cone.

What minimum tail strike guard (stinger) ground clearance indicates yielding cross-tubes on an empty R22 Beta or Beta II?

Less than $34\text{ inches}$ ($34''$) off the ground.

At what wear threshold must the skid shoes on an R22 be replaced?

When the thinnest point of a skid shoe is less than $\frac{1}{16}\text{ inch}$ ($1/16''$).

What are the four primary movements of a helicopter rotor blade?

Feather (rotation along span-wise axis), flap (vertical movement), teeter (flapping in unison about a central hinge), and lead/lag (fore-and-aft movement within the plane of rotation).

What component inside the main rotor blade grip housing allows the blade to feather?

Spindle bearings inside the hermetically sealed blade grip housing.

What is the function of the teeter hinge on the Robinson main rotor hub?

It allows the two rotor blades to teeter and flap as one unit in unison like a seesaw.

What is the primary function of the scissor links on the rotor mast assembly?

They keep the rotating swashplate aligned with the pitch horns and prevent the pitch links from bearing rotational strain.

What are the physical dimensions and twist specification of the R22 main rotor blades?

A diameter of $25'\text{ }2''$, a chord width of $7''$, symmetrical airfoil section, and a twist of $-8^\bot$ from root to tip.

What is the design and orientation of the tail rotor Delta 3 hinge on the R22?

It is an offset teetering hub set at approximately a $45^\bot$ flapping axis angle that couples flapping with pitch changes to minimize tail rotor flapping clearance.

What are the dimensions and coning characteristics of the R22 tail rotor blades?

Diameter of $3'\text{ }6''$, chord of $4''$, asymmetrical airfoil, zero twist, and a fixed coning angle of $1^\bot 11'$.

What engine models power the R22 Beta and Beta II, and what are their base ratings?

Lycoming O-320-B2C rated at $160\text{ BHP} @ 2700\text{ RPM}$ (Beta) and Lycoming O-360-J2A rated at $145\text{ BHP}$ derated from $180\text{ BHP} @ 2700\text{ RPM}$ (Beta II).

What are the Maximum Continuous Power (MCP) and 5-minute Takeoff Power (TOP) ratings for the R22?

MCP is $124\text{ BHP} @ 2652\text{ RPM}$ ($104\%$ tachometer), and 5-minute TOP is $131\text{ BHP} @ 2652\text{ RPM}$.

What are the published atmospheric lapse rates per $1000\text{ ft}$ of altitude increase?

Lose $1\text{ inHg}$ of manifold air pressure (above critical altitude), lose $1\text{ inHg}$ of barometric pressure, lose $2^\bot\text{C}$, and lose $7\text{ Horsepower}$.

What are the four strokes of an internal combustion reciprocating engine in sequential order?

Intake stroke, compression stroke, power stroke, and exhaust stroke.

What defines engine detonation and what are its primary causes?

An uncontrolled explosive combustion of the fuel/air charge caused by high power settings, excessively lean mixture, or using fuel with an insufficient octane rating.

What defines pre-ignition in an aircraft engine cylinder?

The premature ignition of the fuel/air mixture before the timed spark event while the piston is still on its upward compression stroke.

What atmospheric conditions present the greatest risk for carburetor icing?

Outside air temperatures between $10^\bot\text{C}$ and $20^\bot\text{C}$, relative humidity greater than $60\%$, or the presence of visible moisture.

According to the carburetor temperature gauge caution placard, what action must be taken at low manifold pressures?

Below $18\text{ inHg}$ manifold pressure, ignore the gauge and apply full carburetor heat.

What are the performance penalties associated with applying full carburetor heat?

A loss of $1\text{ to }1.5\text{ inHg}$ of manifold pressure and a reduction in hover ceiling of up to $2000\text{ ft}$.

What component in the upper drive sheave allows autorotation during an engine failure?

A freewheeling unit (one-way sprag clutch) that automatically disengages the rotor system from the engine when engine RPM falls below rotor RPM.

What gear reduction ratio is used in the R22 main rotor gearbox?

An $11:47$ speed reduction ratio.

What gear ratio is used in the R22 tail rotor gearbox?

A $3:2$ speed increase ratio.

What engine oil types and quantities are specified for the R22?

Straight mineral oil for the first $50\text{ hours}$ after overhaul and ashless dispersant thereafter, with a sump capacity of $4\text{ to }6\text{ quarts}$ weighing $7.5\text{ lb/gal}$.

What are the color codes for 100LL aviation gasoline and Jet-A turbine fuel?

100LL is blue, and Jet-A is clear.

How much usable fuel remains when the low fuel warning light illuminates in the R22?

Approximately $1.5\text{ gallons}$ of usable fuel.

What three helicopter axes of movement are shown in this reference diagram?

The longitudinal axis (roll), the lateral axis (pitch), and the vertical axis (yaw).

What is the difference in function between the engine governor and the correlator?

The correlator is a mechanical linkage that makes large throttle adjustments as collective is moved; the governor is an electric motor operating above $80\%\text{ ERPM}$ that makes electronic fine-tuning adjustments.

What are the electrical ratings of the R22 battery and alternator?

A $12\text{-volt}$, $25\text{ ampere-hour}$ battery and a $14\text{-volt}$, $60\text{ ampere}$ alternator.

At what crankshaft timing points do the spark plugs fire during start versus normal engine operation?

At Top Dead Center (TDC) via retard breaker points during starting, and at $25^\bot\text{ BTDC}$ (Before Top Dead Center) during normal operation.

What is the maximum allowable magneto RPM drop during run-up testing?

A maximum drop of $7\%$ within $2\text{ seconds}$.

What instruments continue to receive battery power via the bypass circuit during an electrical fire in-flight shutdown?

The dual tachometers (engine and rotor RPM) and the clock, provided the clutch switch remains engaged.

From which components do the engine tachometer and rotor tachometer derive their respective RPM signals?

The engine tachometer receives signals from the right magneto breaker points; the rotor tachometer receives signals from magnetic sensors on the main gearbox drive yoke.

According to the R22 Limit Manifold Pressure placard, how much additional manifold pressure is permitted for 5-minute maximum takeoff power?

Add $0.9\text{ inHg}$ to the maximum continuous power value.

Which instruments are connected to the pitot tube versus the static port?

The pitot tube connects exclusively to the Airspeed Indicator (ASI); the static port connects to the ASI, Altimeter (ALT), and Vertical Speed Indicator (VSI).

How does the Vertical Speed Indicator (VSI) create a differential pressure to measure climb and descent rates?

Direct static pressure feeds the expandable diaphragm, while static air enters the case through a restricted calibrated leak, creating a temporary pressure differential during altitude changes.

How do the pitot-static instruments react if both the pitot tube and its drain become completely blocked in flight?

The altimeter and VSI operate normally, while the airspeed indicator freezes and begins behaving like an altimeter (reading high in a climb, low in a descent).

How do the pitot-static instruments respond if the primary static port becomes blocked?

The altimeter freezes, the VSI reads zero, and the airspeed indicator acts as a reverse altimeter (reading lower than actual in a climb, higher in a descent).

What compass card mounting error card is shown beneath the magnetic compass?

A compass deviation card (correction card), which lists heading compensation values determined on a compass swing.

What is the navigational rule of thumb for converting True Heading to Magnetic Heading with magnetic variation?

'East is Least, West is Best' (subtract easterly variation, add westerly variation).

What compass behavior does the acronym ANDS describe during flight on East or West headings in the Northern Hemisphere?

Accelerate North, Decelerate South.

What compass behavior does the acronym NOSE describe when turning through North or South headings?

North Opposite (compass initially indicates a turn in the opposite direction), South Exaggerated (compass leads the turn at an exaggerated rate).

What hand grip error shown here can prevent the governor from regulating engine RPM?

A 'death grip' on the collective twist-grip throttle, which mechanically overrides the electric governor motor.

What immediate dual control action must a pilot initiate to recover from rotor RPM decay?

Simultaneously lower the collective to reduce blade drag and roll on throttle to restore RPM into the normal operating green arc.

At what rotor RPM threshold does an unrecoverable low RPM rotor stall occur in an R22?

At approximately $80\%\text{ RRPM} + 1\%\text{ per } 1000\text{ ft}$ of density altitude.

Why does a low-G condition induce a rapid right roll in American-rotation helicopters like the R22?

When the main rotor disk is unloaded and produces little thrust, tail rotor thrust located above the center of gravity and horizontal stabilizer negative lift roll the fuselage right.

What is the proper recovery procedure when experiencing an unloaded low-G condition?

Apply gentle aft cyclic first to reload the main rotor disk with positive G, and only then apply lateral cyclic to correct roll attitude.

What airspeed should an R22 pilot reduce to when encountering moderate or severe turbulence?

Reduce airspeed to $60\text{ to }70\text{ knots}$.

What are the three primary energy storage 'batteries' available to a helicopter pilot in autorotation?

Height (potential energy), forward speed (kinetic energy), and rotor RPM.