2025-12-22 – Weekly Helicopter News : Snack machine caused HUMS fault

Last week on the forum, we had a mix of technical queries and practical discussions. Members shared insights into optimizing flight patterns and discussed the nuances of torque measurement on rotor heads. There was also a lively thread on resolving unexpected HUMS (Health and Usage Monitoring Systems) faults triggered by non-flight activities, which sparked a lot of interest. Overall, the conversations were rich with technical expertise and problem-solving.


This Week’s Hot Topics

Left base to a helipad, really
This discussion delves into the complexities and considerations pilots face when approaching a helipad from a left base. It’s a nuanced topic that affects safety and efficiency.
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Electronic torque vs split-beam on rotor head
Here, members are weighing the benefits and drawbacks of different torque measuring methods. It’s a critical conversation for those looking to fine-tune rotor performance.
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Looking for open HUMS datasets
A call for collaboration as members search for open datasets to improve HUMS analysis. This could be a great opportunity for data enthusiasts in aviation.
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Optimizing loop vs out-and-back legs
Pilots are discussing the strategic choices between loop routes and out-and-back legs, with a focus on fuel efficiency and mission planning.
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Hunting drag at 110 knots
This topic explores techniques for reducing drag at high speeds, a critical factor for performance and fuel economy.
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Snack machine triggered a HUMS fault
An unexpected twist where a snack machine caused a HUMS fault, leading to a fascinating discussion on system sensitivities and troubleshooting.
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Best cockpit workflow for EW cueing
Members are sharing their best practices for electronic warfare cueing in the cockpit, aiming to enhance operational effectiveness.
Read more here

Cleaner 1/rev with ACES on a 206
This thread looks into achieving smoother operations with ACES systems on a Bell 206, focusing on vibration reduction.
Read more here


Looking forward to seeing more of your contributions and expertise in the coming week. Stay safe and keep the discussions going strong.

We had a HUMS spike when the snack machine kicked on next to Bay 3; the fix was to gate alerts on WOW/NR (no events until >90% Nr) and use a separate “Ground” acquisition profile during power‑ups so hangar vibrations don’t count. Small caveat: that gating can hide a run‑up clue, so we arm a short run‑up capture once we’re on the ramp; quick primer if anyone needs it: https://skybrary.aero/articles/health-and-usage-monitoring-systems-hums.

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@sally_ht302 We saw GPU/compressor noise tripping HUMS; enabling a 60/400 Hz notch, adding a 2–3 s arming delay after WOW goes false, and clipping a ferrite on the accel lead made it disappear. If you’re gating at >90% Nr, try a low-Nr ‘transient’ profile with higher thresholds so you don’t miss early bearing chatter during spool‑up — snack machines punch above their weight.

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We had our bay’s vending motor fool HUMS too; the clean fix was requiring tach‑synchronous coherence with 1/rev and 2/rev before promoting an alert, so 60 Hz junk dropped to advisory while true rotor orders still flagged. Small caveat: include expected gear‑mesh orders in that allowlist or you’ll hide early chatter during spool‑up — @sally_ht302 do you whitelist mesh freqs as well?

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Quick datapoint from our hangar: we traced “mystery” HUMS alerts to the DAU sharing a breaker with the soda machine. Moving the DAU/sensor power to a clean feed and re-terminating the accel shield to a single-point ground at the rack (floating at the sensor) cleared it; we also added a short bonding strap across the bay door hinge. If rewiring’s a pain, @sophie_lee_47’s filtering angle helps, but watch for ground loops — gremlins love a leaky shield drain.

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