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Colombian commercial helicopter pilot PCH theory foundations study materials
Colombian commercial helicopter pilot PCH theory foundations study resources

Colombian commercial helicopter pilot PCH theory foundations practice questions

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Question 1Rotor controls and transmission

What does the freewheeling unit (overrunning / sprag clutch) allow after an engine failure?

  1. The engine to keep driving the rotor at all costs
  2. The main rotor to continue turning independently so the helicopter can autorotate Correct answer.
  3. The tail rotor to stop while the main rotor keeps turning under power
  4. Automatic restart of a failed turboshaft

Explanation

The freewheeling unit disconnects the engine from the rotor drive when engine RPM falls below rotor RPM. That one-way drive lets the rotor autorotate and keep producing lift after a power failure. Without it, a seized or stopped engine would drag the rotor down.

Question 2Rotor controls and transmission

Raising the collective in a hovering helicopter primarily does which of the following?

  1. Increases blade pitch on all main-rotor blades together, increasing thrust Correct answer.
  2. Changes only the tail-rotor pitch
  3. Feathers the advancing blade and stalls the retreating blade by design
  4. Disconnects the freewheeling unit

Explanation

Collective pitch changes the angle of attack of all main-rotor blades equally, increasing or decreasing total rotor thrust. Cyclic then tilts the disc for directional control. Collective does not command the freewheeling unit and is not a mechanism that deliberately stalls one blade.

Question 3Rotor controls and transmission

A rotor governor (or correlator plus governor) is fitted so that when the pilot raises collective in a hover, which parameter is held near the target?

  1. Manifold pressure on a turbine with no fuel control
  2. Cabin differential pressure
  3. Hydraulic pressure only
  4. Rotor/engine RPM (Nr/N2), by adding fuel as power demand rises Correct answer.

Explanation

Raising collective increases blade pitch and the torque the rotor demands. A governor senses RPM and adds fuel so Nr stays in the green; a correlator makes an approximate throttle/fuel change with collective. Without that, Nr would droop as soon as collective came up.

Question 4Rotor controls and transmission

If the freewheeling unit fails in the engaged (locked) position and the engine then seizes, the most serious immediate effect is that:

  1. The tail rotor will automatically go to full pitch
  2. Autorotation may be impossible because the seized engine can drag rotor RPM down Correct answer.
  3. The hydraulic system will overpressurise
  4. The governor will overspeed the rotor to Vne

Explanation

A freewheeling unit that cannot unlock keeps the engine mechanically connected to the rotor. A seized or rapidly decelerating engine then drives Nr down with it, removing the stored rotor energy needed for autorotation. That is why clutch integrity is a commercial go/no-go item after unusual engine/rotor needle behaviour.

Question 5Rotor controls and transmission

On a dual-needle tachometer (engine RPM and rotor RPM), needles that are joined in powered flight and then split after an engine failure indicate:

  1. The freewheeling unit has disconnected and the rotor is autorotating Correct answer.
  2. The governor has failed to a high-side runaway
  3. The transmission chip detector has failed
  4. The needles are always split in normal cruise

Explanation

Joined needles mean the engine is driving the rotor. After a power failure the engine needle falls while Nr is preserved by lowering collective; the split confirms the freewheeling unit has released. In normal powered cruise the needles remain matched in the green.

Question 6Rotor controls and transmission

Worn or inoperative blade lead-lag dampers on an articulated rotor are most closely associated with which ground hazard?

  1. Ground resonance Correct answer.
  2. Retreating-blade stall in the cruise
  3. Carburettor ice
  4. Transponder failure

Explanation

Lead-lag dampers keep articulated blades from oscillating in the plane of rotation. If they are weak, a landing-gear oscillation can couple with blade imbalance and produce destructive ground resonance. Retreating-blade stall is a high-speed aerodynamic event in flight, not a damper-on-the-ground problem.

Question 7Powerplant and helicopter systems

A main-gearbox chip-detector light illuminates during a commercial sling flight. What does that indication most directly mean?

  1. The fuel filter is bypassing and power will increase
  2. Ferromagnetic particles are being collected from the oil, indicating possible internal gear or bearing wear Correct answer.
  3. The hydraulic reservoir is empty
  4. The indication is a scheduled 100-hour inspection reminder

Explanation

A chip detector is a magnetic plug in the gearbox oil circuit. Illumination means metal particles have closed the detector circuit, a classic sign of gear or bearing distress. Commercial crews treat it as an abnormal gearbox event and follow the AFM, which generally calls for a landing and inspection - not continued sling work.

Question 8Powerplant and helicopter systems

A turboshaft 'hot start' is best defined as:

  1. Any start performed when OAT is above 30 degrees C
  2. A start with the rotor brake left on
  3. A start in which turbine temperature (TOT/ITT/EGT) exceeds the start limit Correct answer.
  4. A start that takes longer than 10 seconds even with temperatures in limits

Explanation

A hot start is an overtemperature during start - TOT, ITT, or EGT above the AFM start limit - usually from excess fuel or insufficient airflow. It can damage turbine section hardware. OAT alone, a rotor brake, or a slow but in-limit start do not define a hot start.

Question 9Powerplant and helicopter systems

In a free-turbine turboshaft, which statement is correct?

  1. The compressor is omitted so the rotor can autorotate
  2. The power turbine is mechanically locked to the gas-producer turbine at all times
  3. There is no combustion section
  4. The gas-producer (N1) section is aerodynamically coupled to a free power turbine that drives the reduction gearbox Correct answer.

Explanation

In a free-turbine engine the gas-producer spool compresses and burns air to drive its own turbine, while a separate power turbine extracts energy to drive the gearbox and rotors. There is no shaft locking N1 to the rotor, which eases starting and protects the rotor after an N1 seizure. The compressor and combustor are still present.

Question 10Powerplant and helicopter systems

Why does a helicopter transmission typically have an oil cooler and a monitored oil temperature, rather than relying on 'ambient air at high density altitude' alone?

  1. Gearbox oil temperature is not a certified limitation
  2. Cooling demand falls to zero in a hover
  3. Reduction gears dissipate large amounts of heat under torque; high density altitude reduces cooling-air density just when hover torque is highest Correct answer.
  4. The cooler exists only to heat the cabin

Explanation

The reduction gearbox turns high torque at relatively low rotor RPM and sheds heat into the oil. Hover, especially OGE at high density altitude, combines high torque with thin cooling air, so oil temperature can climb quickly. That is why commercial crews treat gearbox temperature as a hard operating limit, not a cabin heater.

Question 11Hover performance, loading and margins

Compared with an out-of-ground-effect (OGE) hover at the same weight, an in-ground-effect (IGE) hover generally:

  1. Requires more power because the ground increases induced flow
  2. Requires less power because the surface reduces induced velocity and induced drag Correct answer.
  3. Requires identical power at any height
  4. Is possible only above 1,000 ft AGL

Explanation

Within about one rotor diameter of a surface, ground effect reduces induced flow through the disc, so less power is needed to hover. OGE removes that cushion and raises power required. Ground effect is a near-surface phenomenon, not a high-altitude condition.

Question 12Hover performance, loading and margins

A 170 lb crewmember sits at a station arm of 65 inches. What is that station’s moment?

  1. 11,050 lb-in Correct answer.
  2. 235 lb-in
  3. 2,615 lb-in
  4. 1,105 lb-in

Explanation

Moment equals weight multiplied by arm: 170 × 65 = 11,050 lb-in. Moments are summed and divided by total weight to obtain CG. Adding weight and arm, or dropping a decimal, are typical calculation errors.

Question 13Hover performance, loading and margins

Empty weight 1,450 lb at 105.0 in, pilot 180 lb at 75.0 in, and fuel 200 lb at 110.0 in. What is the loaded CG?

  1. 98.2 in
  2. 105.0 in
  3. 102.6 in Correct answer.
  4. 110.0 in

Explanation

Total weight is 1,450 + 180 + 200 = 1,830 lb. Total moment is (1,450 × 105) + (180 × 75) + (200 × 110) = 152,250 + 13,500 + 22,000 = 187,750 lb-in. CG = 187,750 / 1,830 ≈ 102.6 in. Using empty CG or the fuel arm as the answer skips the moment sum.

Question 14Hover performance, loading and margins

A helicopter’s maximum certificated mass is 2,800 kg. Current mass without sling is 2,200 kg plus 180 kg of fuel. What is the maximum external-load mass that can be lifted without exceeding maximum mass (ignore other AFM sling limits)?

  1. 600 kg
  2. 180 kg
  3. 2,200 kg
  4. 420 kg Correct answer.

Explanation

Available mass is 2,800 − 2,200 − 180 = 420 kg. The AFM may impose a lower external-load or lateral-CG limit, but from mass alone 420 kg is the arithmetic maximum. Using 600 kg ignores fuel, and using 2,200 kg confuses empty mass with payload.

Question 15Hover performance, loading and margins

For weight-and-balance, a suspended Class B external load is treated as acting through which point?

  1. The main-rotor hub always, regardless of hook location
  2. The cargo-hook attachment (the load hangs on the hook station) Correct answer.
  3. The tail-rotor gearbox
  4. The fuel-tank centroid only

Explanation

A hanging sling load’s weight is applied at the cargo hook. The combined CG is therefore pulled toward the hook station, and a swinging load moves that effective point dynamically. It is not applied at the tail gearbox or fuel tank.

Question 16Hover performance, loading and margins

Empty 2,000 lb at 100.0 in, fuel 300 lb at 102.0 in, crew 180 lb at 70.0 in, and a 400 lb sling on a hook at 98.0 in. What is the combined CG?

  1. 98.1 in Correct answer.
  2. 100.0 in
  3. 102.4 in
  4. 94.0 in

Explanation

Total weight is 2,000 + 300 + 180 + 400 = 2,880 lb. Moment is (2,000 × 100) + (300 × 102) + (180 × 70) + (400 × 98) = 200,000 + 30,600 + 12,600 + 39,200 = 282,400 lb-in. CG = 282,400 / 2,880 ≈ 98.1 in. The sling at 98 in pulls CG slightly forward of empty CG.

Question 17Hover performance, loading and margins

A steady headwind while hovering IGE generally:

  1. Increases power required because the disc is in vortex ring
  2. Reduces power required by providing a form of translational lift Correct answer.
  3. Has no effect on hover power
  4. Always requires more tail-rotor thrust than a tailwind of the same speed

Explanation

Relative wind through the disc, even in a 'hover' relative to the ground, reduces induced flow much as effective translational lift does. Power required therefore falls in a headwind. A tailwind or calm still air does not give that benefit, and a strong tailwind can also degrade tail-rotor effectiveness.

Question 18Hover performance, loading and margins

Pressure altitude is 2,500 ft and OAT is 30 °C. Using the approximation DA ≈ PA + 120 × (OAT − ISA), with ISA ≈ 10 °C at 2,500 ft, what density altitude should you take to the hover charts?

  1. 2,500 ft, because charts are always entered with field elevation
  2. 3,700 ft
  3. 10 °C is already ISA, so DA equals PA
  4. 4,900 ft Correct answer.

Explanation

ISA temperature at 2,500 ft is about 10 °C (15 °C minus roughly 2 °C per 1,000 ft). The deviation is +20 °C. DA ≈ 2,500 + 120 × 20 = 4,900 ft. Enter hover charts with density altitude, not with the lower field elevation, or you will overstate OGE/IGE capability - critical in the Colombian Andes.

Question 19Hover performance, loading and margins

An excessively aft CG in a helicopter is most likely to cause which handling problem?

  1. Too much forward cyclic remaining and a nose-down uncommanded dive at all times
  2. No effect provided total mass is under maximum
  3. Reduced forward cyclic authority and a nose-high attitude, with possible inability to attain forward flight Correct answer.
  4. Automatic increase in rotor RPM

Explanation

An aft CG requires forward cyclic just to hold a level attitude, leaving little cyclic to accelerate or recover a nose-high flare. Being under maximum mass does not authorise an out-of-limit CG. Rotor RPM is governed independently of CG.

Question 20Hover performance, loading and margins

Increasing density altitude, with weight unchanged, will most likely:

  1. Raise IGE and OGE hover ceilings and reduce power required
  2. Have no effect on helicopter hover performance
  3. Lower hover ceilings and increase power required for a given hover Correct answer.
  4. Affect aeroplanes only

Explanation

Thinner air reduces both rotor thrust and engine power available, so more power is needed to hover and the IGE/OGE ceilings fall. That is why Andean pads and hot tropical afternoons are commercial planning problems, not just aeroplane take-off issues.

Question 21Hover performance, loading and margins

An 80 kg load hangs 0.40 m left of the CG datum. What lateral moment must be entered in the lateral CG calculation?

  1. 200 kg·m
  2. 32 kg·m to the left Correct answer.
  3. 0.005 kg·m
  4. 80.4 kg·m

Explanation

Lateral moment = mass × lateral arm = 80 × 0.40 = 32 kg·m to the left. That moment is added to the helicopter’s empty lateral moment and divided by total mass to find lateral CG. Adding mass and arm, or dividing instead of multiplying, misses the envelope check.

Question 22Hover performance, loading and margins

Basic empty 1,100 kg, crew 160 kg, passenger 80 kg, baggage 40 kg, fuel 140 kg; maximum mass 1,600 kg. Can you add a 120 kg sling, and what payload remains before the sling?

  1. No; only 80 kg remains before any sling, so 120 kg would exceed maximum mass Correct answer.
  2. Yes; 120 kg is always allowed if the hook is certificated
  3. Yes; remaining payload is 500 kg
  4. No, because remaining payload is 40 kg of baggage only

Explanation

Current mass is 1,100 + 160 + 80 + 40 + 140 = 1,520 kg. Remaining to 1,600 kg is 80 kg. A 120 kg sling would produce 1,640 kg, over maximum mass. A certificated hook does not raise the aircraft mass limit.

Question 23Hover performance, loading and margins

You plan an IGE hover in a tight courtyard where walls recirculate rotor downwash. Which performance statement is correct?

  1. Confined-area recirculation increases IGE benefit, so use the sea-level IGE chart
  2. Ground effect is independent of nearby obstacles
  3. Recirculation and turbulence can destroy useful ground effect, so power required may approach OGE values Correct answer.
  4. Walls always reduce power required by blocking induced flow

Explanation

Classic IGE assumes an unobstructed surface about one rotor diameter below the disc. In a confined pad, downwash recirculates as vortices and the IGE 'cushion' can disappear, so power required rises toward OGE. Commercial planning therefore treats confined IGE as degraded, not as a bonus.

Question 24Rotary-wing aerodynamic foundations

Retreating-blade stall is most likely in which condition?

  1. IGE hover at light weight and low density altitude
  2. Low-speed autorotation near the ground
  3. High forward speed, high mass, high density altitude, low Nr, and turbulence or high load factor Correct answer.
  4. Vertical climb at low density altitude and light weight

Explanation

In forward flight the retreating blade sees lower relative airspeed and must fly at a higher angle of attack. High true airspeed, weight, density altitude, low rotor RPM, and gust or manoeuvre load push that blade through its critical angle. Hover and slow autorotation are not the high-speed retreating-blade regime.

Question 25Rotary-wing aerodynamic foundations

During a commercial-helicopter slope or skid-contact operation, which sequence describes dynamic rollover?

  1. The retreating blade stalls at Vne
  2. The helicopter pivots about a skid or wheel and the roll continues past the critical angle so cyclic alone cannot stop it Correct answer.
  3. The compressor stalls during a hot start
  4. Ground effect is lost above 1,000 ft

Explanation

If a skid, wheel, or snagged line becomes a pivot, thrust and slope can roll the helicopter past a critical angle. Beyond that angle, cyclic cannot stop the roll; lowering collective is the recovery. It is a ground-contact geometric/thrust problem, not a high-speed blade stall.

Question 26Rotary-wing aerodynamic foundations

Ground effect is significant when the helicopter is approximately:

  1. Within about one main-rotor diameter of a suitable surface Correct answer.
  2. Above 1,000 ft AGL in cruise
  3. Only in a HOGE hover
  4. Only when an external load is attached

Explanation

Induced velocity drops when the surface is within about one rotor diameter, producing IGE. Cruise at 1,000 ft and a true OGE hover are outside that cushion. An external load is not required for ground effect and can even complicate a near-surface hover.

Question 27Rotary-wing aerodynamic foundations

At a high-density-altitude Colombian landing site, which flight regime gives a conventional tail-rotor helicopter the greatest LTE exposure?

  1. Straight-and-level cruise at high IAS
  2. Idle-power autorotation
  3. Ground taxi at flat pitch
  4. Low airspeed, high power, out of ground effect, with relative wind from a critical azimuth Correct answer.

Explanation

LTE is an aerodynamic tail-rotor stall or vortex-ring/weathercock condition at low speed and high anti-torque demand, often with a quartering tailwind. High-IAS cruise gives the tail rotor clean air. It is not a mechanical gearbox failure, though the yaw rate can become unrecoverable if ignored.

Question 28Rotary-wing aerodynamic foundations

On a height-velocity (dead-man’s curve) diagram, which combination is in the hazardous region if the engine fails?

  1. Low height and low airspeed, such as a high hover with little speed Correct answer.
  2. Cruise at the recommended IAS well above the curve
  3. High altitude with normal cruise airspeed
  4. Ground taxi at zero rotor thrust demand

Explanation

The shaded H-V region is where neither height nor airspeed gives enough energy to enter a successful autorotation. A high, slow hover is the classic example. Established forward flight above the curve is the safer commercial profile after take-off.

Question 29Rotary-wing aerodynamic foundations

A low-G pushover in a two-blade teetering-rotor helicopter is hazardous primarily because of:

  1. Carburettor ice
  2. Ground resonance in flight
  3. Compressor stall
  4. Mast bumping, which can lead to mast separation if cyclic is misapplied while the rotor is unloaded Correct answer.

Explanation

A teetering rotor needs thrust (G) to stay aligned with the mast. In low G the fuselage can roll under tail-rotor thrust while the disc stays level; cyclic then slams the hub into the mast. Recovery is to restore G gently with cyclic, not to snatch aft cyclic. Ground resonance is a surface event.

Question 30Rotary-wing aerodynamic foundations

How does vortex ring state differ from autorotation?

  1. They are the same manoeuvre with different names
  2. Vortex ring is always power-off; autorotation is always power-on
  3. Vortex ring is a powered descent into the rotor’s own downwash; autorotation is a power-off descent with upward flow driving the rotor Correct answer.
  4. Autorotation can only occur IGE; vortex ring can only occur OGE

Explanation

In VRS the engine is producing power but the disc is descending through its wake, so lift collapses. In autorotation the engine is not driving the rotor; relative upward flow in the driving region keeps Nr up. Confusing the two leads to the worst recovery: pulling collective in VRS as if it were a hover.

Question 31Human factors and decision making

Operating commercially from a high Andean helipad (for example near Bogotá’s elevation), a PCH should treat hypoxia risk how?

  1. As a real human-performance threat even in an unpressurised helicopter, because night vision, judgement, and hover precision degrade with altitude Correct answer.
  2. As irrelevant below 18,000 ft for all crew
  3. As a passenger-only problem; pilots are immune
  4. As a problem only in aeroplanes with pressurisation failures

Explanation

Colombia’s commercial helicopter work often starts already at several thousand feet, and night vision and fine motor control degrade well before 18,000 ft. TEM for a PCH includes recognising hypoxia, using oxygen when required, and not attributing poor hover work only to 'high DA'. Pilots are not immune.

Question 32Human factors and decision making

Brownout or whiteout in a desert or snow hover is hazardous mainly because:

  1. Density altitude always decreases in dust
  2. The transmission oil cooler is blocked instantly in every case
  3. Ground effect becomes stronger than OGE charts allow
  4. Visual references disappear and spatial disorientation can lead to drift, descent, and dynamic rollover Correct answer.

Explanation

Recirculated dust or snow removes the visual texture the vestibular system needs in a hover. The helicopter can drift, settle, or roll about a skid before the pilot notices. Commercial technique is to abort, use a different approach path, or wait rather than 'feel' the hover in zero visual cues.

Question 33Human factors and decision making

During a live external-load lift the longline starts a large pendulum and the PIC’s startle response is to chase it with large cyclic. TEM says the undesired aircraft state to avoid is:

  1. A stable OGE hover with the load allowed to damp
  2. Pilot-induced oscillation, vortex ring if a vertical correction is added, and possible hook or CG exceedance Correct answer.
  3. A planned slow-down of the cyclic to let the pendulum period finish
  4. A radio call to the ground crew only, with no change in flying technique

Explanation

Startle plus a swinging load is a classic TEM chain: large cyclic chases the pendulum, the disc can settle vertically (VRS), and lateral CG can exceed limits. The countermeasure is a stable hover, small inputs, and if needed a load jettison per procedure - not amplifying the swing.

Question 34Weather mechanisms and reports

A PCH reviewing a Colombian aerodrome METAR sees OVC008. How should that sky condition be decoded?

  1. Visibility 8 km
  2. Wind from 080 degrees at 8 kt
  3. Overcast ceiling at 800 ft AGL Correct answer.
  4. Temperature 8 degrees C

Explanation

Sky groups use hundreds of feet AGL. OVC008 is overcast at 800 ft, which is the ceiling. Visibility, wind, and temperature appear in other METAR groups. For a helicopter VFR arrival that ceiling may be the go/no-go item.

Question 35Weather mechanisms and reports

The primary reason a commercial helicopter should remain well clear of thunderstorms is:

  1. Thunderstorms always improve visibility under the core
  2. Severe turbulence, gust fronts, microbursts, hail, and lightning Correct answer.
  3. Thunderstorms reduce density altitude to sea-level values
  4. Lightning charges the battery usefully

Explanation

Cumulonimbus produces extreme helicopter hazards: turbulence that can exceed structural and retreating-blade limits, outflow winds, microburst shear on approach, hail, and lightning. Hovering or sling work near a storm outflow is a common Andean afternoon trap. Distance, not 'scooting under', is the commercial defence.

Question 36Weather mechanisms and reports

A small, decreasing temperature–dew-point spread typically indicates:

  1. Falling relative humidity and improving visibility
  2. Dry downslope winds as the only possible outcome
  3. Rising relative humidity and an increasing chance of fog or low stratus Correct answer.
  4. A guaranteed thunderstorm within 10 minutes

Explanation

When temperature and dew point converge, relative humidity approaches 100 percent and condensation (fog, mist, stratus) becomes likely, especially with cooling and light wind. That is a classic VFR helicopter trap at dawn in valleys. It does not by itself guarantee a thunderstorm.

Question 37Weather mechanisms and reports

For helicopter hover planning, density altitude combines which meteorological influences?

  1. Runway slope only
  2. Pressure, temperature, and humidity as they affect air density Correct answer.
  3. Magnetic variation
  4. UTC offset

Explanation

Density altitude is pressure altitude corrected for non-standard temperature (and humidity reduces density further). High DA means less rotor thrust and less engine power. Magnetic variation and time zone are navigation items, not performance density.

Question 38Weather mechanisms and reports

A SIGMET (WS) is issued for weather that is:

  1. Significant to the safety of all aircraft, such as severe icing, severe turbulence, dust/sandstorms, or volcanic ash Correct answer.
  2. A routine METAR special for one airport only
  3. Light turbulence affecting ultralights exclusively
  4. A NOTAM about a closed taxiway

Explanation

SIGMETs warn of phenomena hazardous to every aircraft, including severe icing and turbulence, widespread dust or sand, and volcanic ash. AIRMETs cover lower thresholds for lighter aircraft. NOTAMs are facility/airspace status, not meteorological SIGMETs.

Question 39Weather mechanisms and reports

Entering a microburst on a helicopter approach typically produces which performance sequence?

  1. A steady tailwind only, with no downdraft
  2. Calm winds and a spontaneous climb
  3. An increasing headwind (apparent performance gain), then a strong downdraft, then a performance-losing tailwind Correct answer.
  4. A gradual headwind that never reverses

Explanation

A microburst is a compact downward burst: first a headwind increase that can fool the pilot into reducing power, then a downdraft, then a tailwind that dumps airspeed and climb capability. Helicopters on steep approaches to pads are fully exposed. The commercial response is to avoid the storm outflow, not to 'ride' the first headwind.

Question 40Weather mechanisms and reports

On a hot afternoon at a high Colombian plateau aerodrome, why can density altitude exceed field elevation by several thousand feet?

  1. Humidity and temperature corrections are never applied in the tropics
  2. OAT well above ISA, and often moisture, reduce air density so DA is much higher than the elevation printed on the chart Correct answer.
  3. QNH is always 1013 in Colombia, cancelling DA
  4. Helicopters use indicated altitude as DA by definition

Explanation

Chart elevation is a geometric height. Density altitude rises about 120 ft for each degree Celsius above ISA, and humid air is less dense still. High plateau plus tropical heat is why a pad listed at 8,000 ft may perform like 10,000-plus ft. Hover charts must be entered with that DA, not with the AIP elevation alone.

Question 41Weather mechanisms and reports

A PIREP is valuable to a commercial helicopter PIC because it:

  1. Provides a timely, location-specific observation of turbulence, icing, or cloud from an aircraft Correct answer.
  2. Replaces the TAF for the next 24 hours
  3. Is issued only by UAEAC meteorologists on the ground
  4. Forecasts weather two weeks ahead

Explanation

Pilot reports fill gaps between METARs and forecasts with real conditions along a route or at a ridgeline. They supplement, they do not replace, TAFs. Any pilot may file one; they are observations, not two-week forecasts.

Question 42Basic navigation, time and fuel

Before a commercial helicopter flight, current NOTAMs should be reviewed because they:

  1. Issue time-critical information on navaid outages, aerodrome closures, hazards, and airspace changes not yet in the AIP pages Correct answer.
  2. Replace the need for a weather briefing
  3. Are optional if the PIC has flown the route once before
  4. Apply only to scheduled airlines, never to PCH operations

Explanation

NOTAMs close the gap between the AIP’s publication cycle and today’s hazards: a dark helipad, a VOR out of service, a gun-firing area, a crane. Prior experience on the route does not waive the check. Weather remains a separate briefing.

Question 43Basic navigation, time and fuel

You are tracking outbound on the 090° radial FROM a VOR. Your approximate position is:

  1. North of the station
  2. West of the station
  3. Over the station regardless of the radial
  4. East of the station Correct answer.

Explanation

VORs radiate radials FROM the station. The 090° radial is the east radial, so an aircraft tracking 090° FROM is east of the VOR. TO indications and reverse sensing on the back course are common exam traps.

Question 44Basic navigation, time and fuel

Using the 1-in-60 rule, if you are 6 NM off track after 60 NM, what is the track error?

  1. 1 degree
  2. 6 degrees Correct answer.
  3. 10 degrees
  4. 60 degrees

Explanation

The 1-in-60 rule states that 1 NM off track in 60 NM is 1 degree. Therefore 6 NM off in 60 NM is 6 degrees of track error. Closing and opening angles are then applied to regain track. 10 degrees and 60 degrees misapply the ratio.

Question 45Basic navigation, time and fuel

Groundspeed is 75 kt and the remaining distance is 50 NM. What is the time en route?

  1. 50 minutes
  2. 75 minutes
  3. 30 minutes
  4. 40 minutes Correct answer.

Explanation

Time (hours) = distance / groundspeed = 50 / 75 = 0.667 h. In minutes that is 0.667 × 60 = 40 minutes. Using TAS instead of GS, or treating 50 NM as 50 minutes regardless of speed, are common commercial-planning errors - especially with Andean headwinds.

Question 46Basic navigation, time and fuel

Squawk 7700 on the transponder means:

  1. Emergency Correct answer.
  2. Radio failure
  3. Unlawful interference
  4. VFR conspicuity in all airspace with no emergency

Explanation

7700 is the general emergency squawk. 7600 is radio failure, 7500 is unlawful interference. A routine VFR conspicuity code is assigned by ATS or published in the AIP (often 7000 or a local code), not 7700.

Question 47Basic navigation, time and fuel

You fly from an area where QNH is 1023 hPa toward one where the actual QNH is 1013 hPa without updating the subscale. Using 30 ft per hPa, what is the altimetry error?

  1. The altimeter overreads by about 300 ft, so you are lower than indicated ('from high to low, look out below') Correct answer.
  2. The altimeter underreads by 300 ft, so you are higher than indicated
  3. There is no error because helicopters use radio altimeter only
  4. The error is 10 ft, equal to the 10 hPa change

Explanation

A 10 hPa fall in QNH with the old setting left in makes the altimeter read about 300 ft too high (10 × 30 ft). True altitude is lower than indicated - the classic 'high to low, look out below' trap in Andean valleys. Radio altimeters help near the surface but do not replace QNH discipline en route.

Question 48Basic navigation, time and fuel

In ICAO radiotelephony, the numeral 9 is spoken as:

  1. NINER Correct answer.
  2. NINE
  3. NOVO
  4. NUEVE only, even on an English frequency

Explanation

Standard ICAO English RTF uses NINER for 9 to avoid confusion with German 'nein' and similar sounds. Official Colombian ATS may use Spanish on some frequencies, but the PCH knowledge item still includes ICAO English numerals for English-language communications. 'NUEVE only' is not the ICAO English form.

Question 49Rotary-wing aerodynamic foundations

What primarily causes settling with power (vortex ring state) in a helicopter?

  1. Loss of tail rotor thrust at altitude
  2. Excessive forward airspeed in level cruise
  3. Operating in the helicopter's own downwash at low airspeed with high power and a vertical or near-vertical descent Correct answer.
  4. Carburetor ice during descent

Explanation

Vortex ring state develops when the rotor descends into its own downwash at low forward airspeed (typically under ~ETL speed) with a descent rate combined with power applied, recirculating air through the rotor and reducing lift.

Question 50Rotary-wing aerodynamic foundations

Retreating blade stall in a single-rotor helicopter is most likely at which condition?

  1. High forward airspeed, high gross weight, high density altitude, and turbulence Correct answer.
  2. Hover in ground effect at light weight
  3. Low airspeed autorotation near the ground
  4. Vertical climb at low density altitude

Explanation

As forward airspeed increases, the retreating blade must operate at higher angles of attack to maintain lift symmetry; high speed, heavy weight, high DA, low rotor RPM, and turbulence increase the chance the retreating blade exceeds its critical angle and stalls.