AAIB Bulletin: 3/2007

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78 © Crown copyrght 2007 AAIB Bulletin: 3/2007 G-OLIZ EW/G2006/10/21 ACCIDENT Aircraft Type and Registration: Robinson R22 Beta, G-OLIZ No & Type of Engines: 1 Lycoming O-320-B2C piston engine Year of Manufacture: 988 Date & Time (UTC): 30 October 2006 at 1439 hrs Location: Falhouse Lane, Whitley, Dewsbury, West Yorkshire Type of Flight: Prvate Persons on Board: Crew -  Passengers - None Injuries: Crew -  (Mnor) Passengers - N/A Nature of Damage: Extensve Commander’s Licence: Prvate Plot’s Lcence Commander’s Age: 4 years Commander’s Flying Experience: 03 hours (of whch 20 were on type) Last 90 days - 8 hours Last 28 days - 5 hours Information Source: Arcraft Accdent Report Form submtted by the plot Synopsis Durng the ntal clmb at slow speed, the plot was aware of the engne seemng to “splutter” and he ncreased the collectve nput. The low rpm horn then actvated and, assumng an engne falure, the plot lowered the collectve and carred out a forced landng nto some trees. The helcopter was extensvely damaged durng the landng. No malfuncton was subsequently identified with the engine and the pilot consdered that the apparent engne problem may have been the result of carburettor cng. History of the flight The pilot had planned a local flight from his private helcopter ste. The weather was good wth an ar temperature of 4ºC. Usng a wndsock postoned on top of a hangar adjacent to the ste, the plot assessed the surface wnd as north to north-westerly at less than 0 kt. Engne start was normal and the plot allowed the engne to warm up for approxmately 0 mn. He then checked the carburettor heat functon and appled partial carburettor heat before hover taxiing G-OLIZ backwards to maxmse hs takeoff run. In accordance wth hs normal procedures, the plot planned to avod some neghbourng propertes and so he used a north-easterly departure drecton. For the departure, the plot used almost maxmum rated power n order to clear a lne of trees, whch were approxmately 25 ft hgh. He was aware that the helcopter was close to the tops of the trees as he cleared them wth the arspeed 79 © Crown copyrght 2007 AAIB Bulletin: 3/2007 G-OLIZ EW/G2006/10/21 at about 25 kt. As he crossed the trees, the plot heard the engne “splutter”. He mmedately pulled on the collectve control, whle also swtchng off the rpm governor and pullng the carburettor heat control to maxmum. He was then aware of hearng the low rpm horn soundng together wth the helcopter yawng to the rght. He assumed the engne had faled and so he responded by lowerng the collectve control. At an estmated heght of 30 to 40 ft agl, the plot had no opton other than to prepare for a forced landng and he amed for some trees n an attempt to cushon the ground mpact. The helcopter struck a large tree, turned through about 80º and landed on ts rght sde. The plot was able to get out through the passenger door. Once outside, there was a strong smell of fuel and so he reached back nto the cockpt to close the fuel shut-off valve and turn off the electrcs master swtch. Post accident assessment The helcopter was extensvely damaged but no pre-impact engine malfunction was identified. On reflection, the pilot considered that the initial engine problem probably resulted from carburettor cng. Hs subsequent acton of ncreasng collectve nput would have caused a reducton n rotor rpm. At the tme, the combnaton of low arspeed and low heght meant that G-OLIZ was in the avoid area of the height/ velocity dagram wth lttle possblty of a successful forced landng. Snce the accdent, the plot has cut off the tops of the trees n the area surroundng hs helcopter ste. He has also ncreased the heght of hs wndsock to gve a more accurate ndcaton of the surface wnd.