ASN Wikibase Occurrence # 267497
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| Date: | Saturday 7 October 2017 |
| Time: | |
| Type: |  AgustaWestland AW139 |
| Owner/operator: | Vigili del Fuoco |
| Registration: | I-TNDD |
| MSN: | 31374 |
| Fatalities: | Fatalities: 0 / Occupants: 5 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Monte Casale -
 Italy
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Ambulance |
| Departure airport: | Trento Mattarello Airport |
| Trento Mattarello Airport | |
| Investigating agency: | ANSV |
| Confidence Rating: |  Accident investigation report completed and information captured |
On 7 October 2017, following a call from the 118 Operations Centre, the crew of the AW139 took off from Trento Mattarello Airport at 08:14 to carry out a primary intervention mission at the face of Monte Casale, in Pietramurata (TN), to rescue a boy who had fallen about 20 m while climbing the mountainside. On board the helicopter there were 5 people: pilot, HHO/HEMS CM, TE, doctor and nurse. After locating the injured person at the base of the rock face, located at an altitude of approximately 2100 feet, the TE was initially winched; subsequently, given the condition of the injured person, the doctor and nurse were also winched, essentially in the same place. While only the HHO/HEMS CM and the pilot were on board the helicopter, the pilot reported his suspicion of having grazed the rock with the main rotor blades. Subsequently, the helicopter headed towards the base camp of Pietramurata, where it had originally been agreed with the mountain rescue team to pick up other rescuers.
After landing in Pietramurata, the HHO/HEMS CM carried out a visual check of the rotor, from which it emerged a possible damage that could not be better assessed due to the fact that the blades were rotating under the thrust of the engines in motion. At this point the pilot decided not to shut down the helicopter and to return to Trento Mattarello Airport to perform the necessary checks; during this flight no control problems of the aircraft were detected. Once at destination, it was found that the ends of the 5 main rotor blades were damaged.
Causes
The accident was caused by the impact of the helicopter's main rotor blade tips against a rock face, due to pilot's inadequate assessment of blade distance.
The following factors reasonably contributed to the occurrence of the event
- at the organisational level, the absence in the cockpit of the HEMS CM who could have provided support to the pilot's assessments and decisions;
- the greyish-yellow background of the rock face in front of which the helicopter was positioned orthogonally, which did not help the pilot to determine the distance of the main rotor blades from the rock face, taking into account that the blades are painted yellow in the last part to define their outer limit, thus blending in with the background of the rock face;
- the absence of equipment on board the helicopter to assist the pilot with regard to the distance from obstacles.
Following the contact of the main rotor blades with the rock face, mental mechanisms were triggered which compromised the pilot's ability to:
- correctly assess the damage to the helicopter;
- correctly evaluate the risks deriving from a transfer flight lasting several minutes with an aircraft that had been damaged in one of its "vital" parts.
This critical assessment was probably induced:
- by the fact that the on-board systems had not detected any anomalies and that the helicopter did not present any controllability problems;
- by the assessment that stopping the helicopter at the base camp where it had landed after the damage would have complicated and delayed its subsequent transfer to the armament base for maintenance operations, with a possible delay in restoring its efficiency;
- the self-induced and perceived pressure of the pilot, who was aware that the social and media attention on the Fire Brigade Helicopter Unit of the Autonomous Province of Trento could have highlighted and publicised what had happened, thus adversely affecting the image of the Unit.
Accident investigation:
 |
|
Sources:
ANSV
http://aerossurance.com/helicopters/alps-aw139-sar-blade-strike/
Media:
While undertaking a hoist rescue this Italian AW139 suffered a main rotor blade strike. We look at the ANSV investigation. https://t.co/jd6mibDdxD #helicopter #searchandrescue #sar pic.twitter.com/uydGD2KUi4
— Aerossurance (@Aerossurance) November 7, 2021
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 10-Sep-2021 08:29 | harro | Added |
| 10-Sep-2021 08:30 | harro | Updated [Cn, Operator] |
| 07-Nov-2021 13:33 | Aerossurance | Updated [Total occupants, Destination airport, Source, Embed code] |
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