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Private/Commercial — Helicopter (Robinson)
SFAR 73 Oral Exam Questions: R22 & R44 Checkride Prep
If your checkride is in a Robinson R22 or R44, expect Special Federal Aviation Regulation 73 to anchor a chunk of the oral. SFAR 73 exists because of a series of fatal accidents involving low-G mast bumping and low rotor RPM blade stall in these light, low-inertia-rotor helicopters; it mandates awareness training on specific subjects plus experience/endorsement requirements before acting as PIC, plus aircraft-specific flight training and recurring requirements.
The examiner's questions go beyond 'what does the SFAR require' into 'do you actually understand the hazards it was written about.' Be ready to teach low-G/mast bumping and low rotor RPM recovery at whiteboard depth — and to state the specific hour/endorsement numbers from the current SFAR text, which you should re-verify shortly before your ride rather than trusting any secondary source.
What the SFAR requires
SFAR 73 applies to anyone manipulating the controls of an R22 or R44. The centerpiece is awareness training from an authorized (SFAR-qualified) Robinson instructor covering five subjects: energy management; mast bumping; low rotor RPM (rotor stall); low-G hazards and their causes; and rotor RPM decay. You receive a logbook endorsement for it. On top of that sit aircraft-specific dual training and endorsement requirements before solo or acting as PIC, hour thresholds (general helicopter time and in-type time) that determine whether you fly under supervision or with endorsements, and recurring requirements — including flight-review provisions specific to the type (an R22 pilot's flight review taken in an R22, and so on) until you exceed the SFAR's experience gates.
For the oral, organize it as: (1) awareness training — everyone, with endorsement; (2) PIC experience/endorsement gates — the specific hour numbers from the current SFAR; (3) recurrency — what the SFAR says about flight reviews and the 12-month requirements at lower experience levels. Bring a printed copy of the SFAR; reading the actual text with the examiner beats reciting numbers from memory and demonstrates the verification habit the rule rewards.
The hazards behind the rule
Low-G and mast bumping: two-bladed teetering rotor systems require positive G to keep the rotor loaded. An abrupt forward cyclic pushover (or turbulence) can unload the rotor; with no disc loading, main-rotor thrust can't control the fuselage, the helicopter rolls (tail-rotor thrust above the CG rolls it right in Robinsons), and a large corrective cyclic input with an unloaded rotor lets the hub contact ('bump') the mast — which can sever it. Recovery: immediately and smoothly apply aft cyclic to reload the rotor, then level. Never apply lateral cyclic while unloaded. Prevention: no pushovers, slow down in turbulence per the RFM, avoid low-G demonstrations entirely.
Low rotor RPM / rotor stall: low-inertia rotors decay fast; if RPM drops far enough the blades stall, coning increases, and no recovery is possible — this is unrecoverable below a surprisingly small margin, which is why Robinson governors, horns and lights intervene early. Recovery at onset: simultaneously lower collective and increase throttle (in governed ships, still back up the governor), and in forward flight gentle aft cyclic can help recover RPM. Energy management ties it together: rotor RPM is your stored energy for any emergency — protect it above all else.
Practice questions with answers & rationales
Q1. Who does SFAR 73 apply to, and what training does it require for you?
Answer: Anyone who manipulates the controls of a Robinson R22 or R44. At minimum, awareness training from an SFAR-authorized instructor on five subjects — energy management, mast bumping, low rotor RPM (blade stall), low-G hazards, and rotor RPM decay — with a logbook endorsement, plus the aircraft-specific dual training, endorsements and hour gates in the SFAR before solo flight or acting as PIC, and recurring requirements until you pass the experience thresholds. I verify the specific hour numbers against the current SFAR text, which I've brought.
Q2. What is mast bumping and what causes it?
Answer: Contact between the main rotor hub and the rotor mast in a teetering (two-bladed, semi-rigid) system — usually following a low-G condition. Unload the rotor (abrupt pushover, turbulence) and main-rotor thrust no longer controls the fuselage; tail-rotor thrust above the CG rolls the ship right; if the pilot responds with large lateral cyclic while the disc is unloaded, the hub can strike the mast, and a severe bump can separate the mast and rotor. It is typically fatal — which is the level of seriousness the answer should carry.
Q3. You encounter low G after an abrupt pushover and the aircraft starts rolling right. What do you do?
Answer: Smooth, immediate aft cyclic to reload the rotor — first and only first. Once positive G and disc loading are restored, level the aircraft with normal inputs. Applying left cyclic before reloading is the killer error: with the rotor unloaded, cyclic doesn't control the fuselage, but it can drive the flapping that produces mast bumping. Then: slow down, report/inspect per RFM if anything was abnormal.
Q4. Why is low rotor RPM so much more dangerous in an R22 than in a heavier helicopter?
Answer: Blade inertia. The R22's low-inertia rotor stores little rotational energy, so RPM decays extremely fast when power is lost or over-pitched, and the margin between the bottom of the green and unrecoverable rotor stall is small. Once the blades stall, coning increases drag, RPM collapses further, and recovery is aerodynamically impossible regardless of altitude. Hence governors, RPM horns/lights, and the SFAR's obsession with RPM awareness.
Q5. What's the recovery from low rotor RPM at the first horn/light?
Answer: Simultaneously lower the collective (reduce drag/demand) and roll on throttle (restore power) — in a governed Robinson the governor should be doing this, but you back it up manually — and in forward flight, gentle aft cyclic increases inflow and helps the rotor recover. The deeper teaching point: react to the first indication; seconds matter with a low-inertia rotor, and a deeply decayed rotor may already be past saving.
Q6. What does 'energy management' mean in the SFAR 73 awareness syllabus?
Answer: Treating rotor RPM, airspeed, and altitude as the three energy stores you trade between — with rotor RPM as the non-negotiable one. It covers protecting RPM in maneuvers, entering autorotation promptly (the energy to arrive at the flare with RPM, airspeed and a survivable descent rate), and avoiding flight conditions (low RPM + low airspeed + high power demand) where no trade can rescue you. It's the unifying idea behind every other SFAR subject.
Q7. Are there wind/turbulence limitations you should brief for a Robinson flight?
Answer: Yes — Robinson safety notices and the POH/RFM contain specific guidance: reduce airspeed in significant turbulence (flying at reduced cruise speeds lowers low-G risk), avoid flight in high winds/turbulence at high speed, and treat demonstrated-wind hover limits seriously. Quote your model's RFM and the relevant Robinson Safety Notices (e.g., on low-G and low RPM) — examiners in Robinsons frequently ask which safety notices you've read.
Common mistakes to avoid
- Quoting SFAR hour gates from a prep book without re-checking the current SFAR text — the numbers are the first thing examiners verify.
- Explaining mast bumping but giving the wrong recovery (lateral cyclic first). Aft cyclic to reload, always.
- Treating the low-RPM horn as an annoyance rather than the start of a seconds-long countdown.
- Forgetting that awareness training applies to anyone touching the controls — not just solo students.
- Skipping Robinson Safety Notices. They're referenced material on Robinson checkrides; know the low-G and low-RPM ones at minimum.
- Describing a low-G demonstration as something you'd perform. The correct posture: it is never demonstrated or practiced — prevention only.