Preflight Discrepancies, a Puffed Battery, and a Client Pushing
A commercial real-estate client has booked a 45-minute exterior scan of a 6-story building and is paying a rush fee. At the preflight table you find: a 4 mm deep nick on the leading edge of one propeller; a 3S LiPo that reads 12.4 V but is slightly puffy and has a faint sweet smell; a logbook entry from 22 days ago reading 'slight gimbal vibration at high yaw rate - monitor'; and a firmware update notice you have not installed. Wind is forecast 18 kt gusting 26 kt, and the building produces corner turbulence. The client is standing next to you saying the roof access closes in an hour. Your second crew member has never flown this airframe.
1. Work through each discrepancy and state your preflight determination, citing the standard you are applying.
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The governing point is that the preflight rules place the go/no-go on the remote PIC, who must become familiar with all available information about the flight and ensure the aircraft is in a condition for safe operation. 'Monitor' is not a disposition.
- Propeller nick (4 mm, leading edge): this is a control-surface-quality part, not cosmetic. A nick changes balance and loads the hub; vibration from an out-of-balance prop propagates into the motors and frame. Replace the propeller. It costs less than the flight and it is not a part to 'sand and send.'
- Puffed 3S LiPo with a sweet smell: that is electrolyte decomposition, i.e., a cell is venting internally. Voltage (12.4 V ≈ 3.9 V/cell) is irrelevant - a pack can read normally and still be a fire hazard. Retire it: do not charge it, do not fly it, isolate it and dispose of it properly. Fly a known-good pack or do not fly.
- Open logbook item: 'slight gimbal vibration at high yaw rate - monitor' is unresolved. After the prop is replaced, reproduce the condition on the ground and in a short controlled hover. If it persists, the aircraft is not in a condition for safe operation and the flight does not happen.
- Uninstalled firmware: do not install flight-controller firmware immediately before a paid job. New firmware changes behavior you have not tested. Note it and perform it on a non-revenue day with a test flight.
2. The client pressures you to fly anyway. How do you handle the conversation, and what is your decision?
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Decision: no flight today. Nothing in the list is a judgment call once the battery and the prop are on the table, and both the battery and the prop must be resolved before any flight - not just before this flight.
Handle the conversation in terms the client cares about, not a regulation recitation:
- State the finding plainly: 'One of the batteries is failing internally and one propeller is damaged. Flying either one risks the aircraft coming down over your building or your street.'
- Offer a concrete alternative rather than a bare refusal: a partial job from a lower altitude and a longer standoff distance, a rebooking within a defined window, or a refund of the rush fee.
- Do not negotiate on the battery or the prop. A rush fee does not transfer the risk, and the PIC's certificate is the thing on the line.
Document the no-go decision, the reasons, and the time, in the log. A defensible written record is what protects you later.
3. Separately from the hardware, what does the 18 kt gusting 26 kt forecast and the unfamiliar second crew member mean for today's flight?
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Both are independent reasons to expect a hard flight, and both interact with the hardware findings.
- Wind and turbulence: 18G26 kt is a large gust spread, and a 6-story building generates rotor and corner turbulence that is not reflected in the forecast. High gust spread plus turbulence means the aircraft works harder, holds less stable position, and burns more battery - which is exactly the environment where a marginal battery or an out-of-balance prop fails. Check the airframe's published wind limit and treat corner turbulence as the real limit, not the open-field forecast number.
- Crew unfamiliarity: the second crew member has never flown this airframe. Before any flight, brief roles: who is on the controls, who is the observer, who calls traffic, what a 'stop' call sounds like, how control is handed off, and what the lost-link and low-battery actions are. An unbriefed observer is a passenger, not crew.
The takeaway for the exam-style judgment: discrepancies, weather, and crew are not separate checklists. They compound, and the decision is made against the combination.