Following a serious injury received when a propeller detached while an aircraft was at full power being tested for noise, recommendations have been issued to help mitigate this risk. These recommendations apply to the element of the test with the model pointing directly at the meter.
1) Always check the security of the propeller before conducting any noise testing. Guidance on the integrity of multi-bolt attachment of large propellers will be issued following further investigation of the incident.
2) If possible, use a tripod mounted sound level meter (SLM) with a memory function that can store the maximum A weighted sound pressure reading.
3) If the SLM operator has to stand in front of the model, use a “catch” net (see picture below) placed at the midpoint between the aircraft and the SLM. We have conducted trials using cricket practice netting 2m by 2m constructed of 50mm (2") square mesh black polyethylene of 2mm gauge (cost £12.90 inc P&P) . (www.knowlenets.co.uk/leisure/cricket.htm) The trials showed no significant effect on the SLM measurements.
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