Bundesstelle für Flugunfalluntersuchung German Federal Bureau of Aircraft Accident Investigation Investigation Report The Investigation Report was written in accordance with para 18 Law Relating to the Investigation into Accidents and Incidents Associated with the Operation of Civil Aircraft stating facts only. Identification Type of Occurrence: Accident Date: 18 October 2014 Location: Aircraft: Manufacturer / Model: Injuries to Persons: Damage: Other Damage: Information Source: Near Egelsbach Helicopter Hélicoptères Guimbal / Cabri G2 None Aircraft severely damaged None Investigation by BFU external experts for field investigation State File Number: BFU 3X112-14
Factual Information History of the Flight At the day of the accident, the pilot, accompanied by a passenger, wanted to conduct a night flight with a Cabri G2 helicopter from Frankfurt-Egelsbach Airfield (EDFE) to Augsburg Airfield (EDMA). The passenger also held a private helicopter pilot's licence. Both persons stated that at about 1855 hrs 1, shortly after take-off toward the east and after having flown over the local industrial area, they heard hitting noises. The pilot stated he did not have an explanation and therefore wanted to return to the airfield immediately and turned around. He then noticed a sudden loss of rotor rpm, initiated autorotation, and turned back towards the open field they had just overflown. Accident site Departure in EDFE Course of the flight Image: BFU / Google earth TM During the autorotation landing, while the helicopter skidded across the field, the main rotor cut through the tail boom. The helicopter was severely damaged. Both occupants were able to leave the helicopter uninjured. 1 All times local, unless otherwise stated. - 2 -
Personnel Information The 43-year-old pilot held a Commercial Helicopter Pilot's Licence (CPL(H)) issued in accordance with Part FCL. The licence carried the ratings as Pilot in Command (PIC) for AS350/EC130, Cabri G2, EC 120B and R44. In addition, he held the instructor rating for training private and commercial pilots and night flight (FI(H) CPL, PPL, SE SP, ME SP, night). He held a class 1 medical certificate in accordance with Part MED with the restriction VDL valid until 24 October 2014. His total flying experience was about 2,233 hours. Approximately 663 hours of which were acquired on Cabri G2. The 26-year-old passenger held a Private Helicopter Pilot's Licence (PPL(H)) with the ratings as PIC on Cabri G2 and R44. Aircraft Information Hélicoptères Guimbal is the manufacturer of the Cabri G2 two-seated helicopter. It has skids, a three-blade main rotor and a Fenestron for anti-torque. Maximum takeoff mass is 700 kg. The helicopter is equipped with a piston engine Lycoming O-360- J2A. A multi-rip drive belt is used for the power transmission from the piston engine to the main gear box. In 2007 EASA certified the helicopter type according to certification specifications CS-27. The accident helicopter Cabri G2 was built in 2012 and had the manufacturer s serial number 1041. According to the weight and balance report, empty weight was about 428 kg. Total operating hours of the helicopter were about 420 hours. The last Airworthiness Review Certificate (ARC) was issued on 12 November 2013. The helicopter had a German certificate of registration. Unscheduled maintenance work was carried out on 21 March 2014 at 406.3 operating hours and on 25 March 2014 at 408.1 operating hours due to a slipping transmission belt. Maintenance records show that both times the transmission belt was contaminated with oil and grease. On 17 April 2014 at 410.4 operating hours the main gear box was re-sealed due to leakages. On 27 August 2014 at 418.8 operating hours the last Release to Service was issued after scheduled maintenance work in Egelsbach (Lycoming SB 480 and HG SB 14-013). - 3 -
Meteorological Information According to the data from the Deutscher Wetterdienst (German meteorological service provider, DWD) there was a low pressure system north-west of Ireland and a high pressure system reaching from the Alps to East Europe. Very mild air flowed in from the south-west. The stabilising influence of the high pressure system was decisive for the weather during the day and even the following night. According to the aviation routine weather report (METAR) of 1850 hrs of Frankfurt- Main Airport close by, the following weather conditions prevailed at the time of the occurrence: Wind 060, with 5 knots. Ground visibility was more than 10 km and there was no cloud cover below 5,000 ft (CAVOK). Temperature was 15 C and the dewpoint was 14 C. Barometric air pressure (QNH) was 1,021 hpa. Sun set was at about 1829 hrs. Aerodrome Information Frankfurt-Egelsbach Airfield (EDFE) is located west of the city of Egelsbach and about 8 NM south of Frankfurt. The runway is 1,400 m long and has the direction 090 /270. Aerodrome elevation is 385 ft AMSL. Flight Recorders The helicopter was not equipped with a Flight Data Recorder (FDR) or a Cockpit Voice Recorder (CVR). There were no legal requirements for such equipment to be fitted. Wreckage and Impact Information The accident site was located on a field in the area of the Darmstädter Strasse in the departure sector of runway 09. The helicopter stood upright on its skids. At the end of the skid marks which were several meters long, the skids had sunk into the soft ground. The vertical fin including Fenestron had been cut off the tail boom. The Fenestron casing showed circumferential scratch marks; pieces were torn out of it. Two of the seven Fenestron blades had been destroyed. The tail section had broken into several pieces. One of the three main rotor blades showed severe damages and the trailing edge had chapped on the entire length. In the area of the power transmis- - 4 -
sion between engine and main gear box a destroyed transmission belt was found. It had been torn into many strips and pieces. Strips had wrapped around the tail rotor drive shaft. Accident site and damages Photos: BFU After the salvage operation, a closer examination was conducted in the presence of the manufacturer, the insurance company, and the owner. It was determined that the entire area between firewall bulkhead, engine and main gear box, i.e. the area around the transmission belt, was contaminated with oil and grease. Parts of the transmission belt were also contaminated with oil and grease. The rubber rips of the belt felt soft and greasy (see Appendix 1). - 5 -
Damages and determinations in the area of the transmission belt Photos: Manufacturer In the facilities of the manufacturer the helicopter was disassembled. Then it was determined that the left belt guide was bent and did probably not have the proper gap to the transmission belt (see Appendices 2 and 3). Fire There was no fire. -6-
Additional Information The manufacturer stated that until the accident the transmission belt had never failed in this aircraft type. After the accident the manufacturer published the Service Bulletin (SB) 14-026A Transmission Belt Check on 27 October 2014 (see Appendix 4). Investigator in charge: Field investigation: Axel Rokohl Kurt Frieß Braunschweig, 7 November 2014 Appendices Appendix 1: Appendix 2: Appendix 3: Determinations of the Manufacturer Analysis of the Manufacturer Conclusions of the Manufacturer Appendix 4: SB 14-026A of the Manufacturer published on 27 October 2014-7 -
Appendix 1: Determinations of the Manufacturer Appendix 2: Analysis of the Manufacturer - 8 -
Appendix 3: Conclusions of the Manufacturer - 9 -
Appendix 4: SB 14-026A of the Manufacturer published on 27 October 2014-10 -
This investigation was conducted in accordance with the regulation (EU) No. 996/2010 of the European Parliament and of the Council of 20 October 2010 on the investigation and prevention of accidents and incidents in civil aviation and the Federal German Law relating to the investigation of accidents and incidents associated with the operation of civil aircraft (Flugunfall-Untersuchungs-Gesetz - FlUUG) of 26 August 1998. The sole objective of the investigation is to prevent future accidents and incidents. The investigation does not seek to ascertain blame or apportion legal liability for any claims that may arise. This document is a translation of the German Investigation Report. Although every effort was made for the translation to be accurate, in the event of any discrepancies the original German document is the authentic version. Published by: Bundesstelle für Flugunfalluntersuchung Hermann-Blenk-Str. 16 38108 Braunschweig Phone +49 531 35 48-0 Fax +49 531 35 48-246 Mail Internet box@bfu-web.de www.bfu-web.de - 11 -