ASN Wikibase Occurrence # 17655
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| Date: | Monday 7 April 2008 |
| Time: | 09:15 UTC |
| Type: |  Robinson R22 Beta |
| Owner/operator: | Helicopter Training Services |
| Registration: | ZS-RNB |
| MSN: | 3252 |
| Year of manufacture: | 2001 |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Location: | near Grand Central Airport, Midrand, Gauteng Province -
 South Africa
|
| Phase: | Landing |
| Nature: | Training |
| Departure airport: | Grand Central Airport, Midrand, South Africa (GCJ/FAGC) |
| Grand Central Airport, Midrand, South Africa (GCJ/FAGC) | |
| Investigating agency: | CAA S.A. |
| Confidence Rating: |  Accident investigation report completed and information captured |
The flight instructor and a passenger (potential student) had just concluded a demonstration flight in the general
flying area (GFA) south of Grand Central Airport, Midrand, Gauteng Province
The helicopter climbed to 350 ft above ground Level (AGL) when the instructor elected to demonstrate an
auto-rotation to his passenger. The instructor initiated his autorotation demonstration at 350 feet, flying in a northerly
direction with the wind coming from the east. Four to five seconds following the initiation of the autorotation, the
main rotor revolutions per minute (RPM) warning sounded and he made an attempt to open the throttle whilst
lowering the collective pitch control, to no avail. The helicopter landed hard on the skids. The aircraft was
substantially damaged, including failure of the left skid and the tail boom severing.
Both the pilot and passenger were injured in the incident. The pilot had noted shortly after initiating the manoeuvre that his main rotor RPM had decayed to about 88%, which was substantially lower than the norm following entry into autorotative flight. Even though he had immediately unloaded the rotor disc by lowering the collective pitch lever and rolling on the throttle as advised in the pilot’s operating handbook, he was unable to recover from the low RPM condition.
This may have been due to a lack of altitude and the helicopter being in a blade stall state as a result of the low RPM and the fairly high descent rate. He managed to maintain level flight whilst descending and as the ground approached, he attempted to cushion the impact by pulling maximum collective pitch.
However, this had no effect on the rotor system as the rotor system had already stalled. A hard landing followed at a substantial rate of descent, which was evident from the deformation of the skid gear and the subsequent impact sequence and damage to the helicopter
PROBABLE CAUSE: Hard landing following a fairly high descent rate as result of a low rotor RPM/blade stall.
Accident investigation:
 |
|
Sources:
1. http://www.caa.co.za/Pages/Default.aspxAccidents%20and%20Incidents%20Reports/8471.pdf
2. http://www.griffin-helicopters.co.uk/accidents.aspx?Acregn=ZS-
3. http://helicoptertraining.co.za/helicopter-for-sale.html
4. http://www.rotorspot.nl/current/zs-c.php
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 04-May-2008 07:18 | Topaz | Added |
| 30-Sep-2016 12:21 | Dr.John Smith | Updated [Time, Total fatalities, Total occupants, Other fatalities, Location, Phase, Departure airport, Destination airport, Source, Narrative] |
Corrections or additions? ... Edit this accident description
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