# NTSB WPR16LA168: Robinson R44, N74805, Kailua/Kona, HI, August 26, 2016 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 26, 2016, 07:45 local (17:45 UTC) - Place: Kailua/Kona, HI - Coordinates: 19.743055, -156.032775 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=19.7431&lon=-156.0328&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-flare/touchdown: Loss of control on ground](https://openairdocs.org/ntsb-events/230) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report June 25, 2019 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration, Robinson Helicopters - NTSB case key (mKey): 93894 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR16LA168 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/93894/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=93894 - Page: https://openairdocs.org/ntsb/WPR16LA168 ## Probable cause An on-ground upset for reasons that could not be determined because postaccident examination of the helicopter revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined (probable cause); cases with it: [Robinson Helicopter R44 II, 24 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=7640122), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing-flare/touchdown: Loss of control on ground](https://openairdocs.org/ntsb-events/230) (defining event); cases with it: [Robinson Helicopter R44 II, 11 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=7640122), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) - [Landing: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Robinson Helicopter R44 II, 95 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=7640122), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis During aninstructional flight in the helicopter, the pilot under instruction set up for anapproach and landing to a flat and smooth gravel road. Once the skids were on the ground, the pilot under instruction lowered the collective toward the FULL DOWN position. The helicopter then began to rock in a fore and aft motion. The flight instructor took the controls as the intensity of the rocking increased; the helicopter then ascended in uncontrollable flight. The flight instructor subsequently landed the helicopter on the gravel road; it came to rest upright about 20 to 30 ft and at a little more than a 45° angle from the initial touchdown point. The helicopter sustained substantial damage to the fuselage. Postaccident examination of the helicopterrevealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. Thus, the reason for the reported on-ground upset could not be determined. ## Factual narrative On August 26, 2016, about 0745 Hawaii standard time, a Robinson R44 II helicopter, N74805, was substantially damaged following a loss of control after landing at the Kona International Airport at Keahole (HKO), Kailua/Kona, Hawaii. The certified flight instructor (CFI) and pilot under instruction (PUI), who is also a CFI, were not injured. Visual meteorological conditions prevailed during the instructional flight, which was being conducted in accordance with 14 Code of Federal Regulations Part 91, and a flight plan was not filed. The local flight departed HKO about 0715. In a written report submitted to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the CFI/pilot in command, reported that as they entered the North Practice Area (NPA) he instructed the PUI to make the first approach to a spot in the middle of the gravel road, which would provide plenty of clearance. The CFI stated that the spot chosen was one of the gravel roads in the NPA, which has a wide area, and is flat and smooth with no large rocks. The CFI further stated that the PUI began his approach on a left downwind, then turned on to base and final "…and everything was looking great. I told him to complete the approach to a full stop on the ground." The CFI reported that the approach was smooth, and that the initial set down was very soft and smooth as well. The CFI opined that once the skids were on the ground, the PUI continued to lower the collective towards the full down position, at which time the helicopter began to rock in a fore and aft motion. The CFI stated that as the intensity quickly increased he came on the controls, and from that point on all that he could recall was that "…we were in the air again in uncontrollable flight." The CFI reported that the helicopter was oscillating intensely, then came to a stop about 20 to 30 ft and a little more than a 45° angle to the forward and left of the initial touchdown point. The helicopter sustained substantial damage to the fuselage as a result of impact with terrain. In a statement submitted to the NTSB IIC, the PUI reported that he and his instructor departed from Kona Airport around 7:50 am local time, for the North practice area. Everything was good, and he performed a controlled and smooth normal approach to a flat well open area. The skids touched the ground and then a strong rocking aft and forward movement accompanied by heavy vibrations started. He tried to lower the collective but made it worse, so he tried to pick up to correct, then it felt like the helicopter shot out forward/leftwards approximately 10 feet away from landing spot. He recalled that the cyclic did not respond to inputs well enough, and ended up crashing nose first with a main rotor blade strike in the ground, no dynamic rollover happened. As soon as the helicopter stopped moving, the mixture was pulled out to shut down the engine. On October 4, 2016, Federal Aviation Administration aviation safety inspectors assigned tothe Honolulu Flight Standards District Office, Honolulu, Hawaii, examined the helicopter. The tailcone cowling attach points were inspected with the tailcone installed. No damage or defects were noted. The torgue on the tailcone attaching hardware using a calibrated torque wrench was checked. The torque was 655-inch pounds per the manual. The torque broke (nut moved) at 355-inch pounds on all bolts. Additionally, the tailcone was removed and no elongation or damage to the bolts, washers, skin or structure were noted. Flight Control Servos and Push-Pull Tubes With the mast fairing removed, the main rotor torque tube, control tubes and servos were examined. No damage or defects were noted. The flight controls were moved through a full range of motion with and without hydraulic power. Control continuity and operation appeared to be normal. Main Rotor Gearbox Mounts The main rotor gearbox mounts were inspected with the tailcone and both fuel tanks removed. The inspection of the mounts' rubber portion, as well as the associated ears of the mounts, revealed no damage or defects. Using a calibrated torque wrench, the torque registered on the main transmission bolts was 90-foot pounds, which was consistent with the value denoted in the maintenance manual. ## Aircraft - Registration: [N74805](https://openairdocs.org/deregistered/N74805-2018-12-18), registration cancelled 2018-12-18, S/N 10934, built 2005 (OpenAirDocs) - Reported make and model: ROBINSON R44 (II) - Registry model: [Robinson Helicopter R44 II](https://openairdocs.org/model/robinson-helicopter-r44-ii) (registry code 7640122) (OpenAirDocs) - Registry engine: [Lycoming IO-540 series](https://openairdocs.org/engine/lycoming-io-540-series) (registry code 41530, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 10934 - Year built: 2005 - Airframe hours: 5747 - Engines: Lycoming IO-540 300 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, July 14, 2016, 80 hours before - Departed: KOA, Kailua/Kona, HI - Destination: KOA, Kailua/Kona, HI - Airport: KOA, Kona International Airport - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 45; injuries: none; commercial, flight instructor; instrument ratings: helicopter; medical: class 2, without waivers/limitations; last flight review June 2, 2016; seat: left; restraint: 3-point; flight hours: 650 total, 74 in this make and model, 565 as pilot in command, 126 in the last 90 days, 43 in the last 30 days, 2 in the last 24 hours - Student pilot; age 28; injuries: none; flight instructor, commercial; medical: class 3, unknown; last flight review June 24, 2016; seat: right; restraint: 3-point; flight hours: 198 total, 16 in this make and model, 128 as pilot in command, 5 in the last 90 days, 4 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 150° at 11 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 79 °F, dew point 73 °F - Altimeter: 29.96 inHg - Observed at: HKO, 1 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20160826025019A](https://openairdocs.org/incident/20160826025019A), Aug 26, 2016: Robinson Helicopter Company R44 II, Kailua Kona, HI, Substantial damage. 8/26/16 A R44 piloted by student [privacy data omitted] and CFI [privacy data omitted] after a soft landing went into an uncontrollable wobble, momentarily… ## Docket (5 files) The files NTSB released with the investigation on April 30, 2019, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=93894. 12.7 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 2.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40458715&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Pilot Statements (item 2, .PDF, 133 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40458717&FileExtension=.PDF&FileName=Pilot%20Statements-Master.PDF - FAA Inspector's Examination Report (item 3, .PDF, 348 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40458719&FileExtension=.PDF&FileName=FAA%20Inspector%27s%20Examination%20Report-Master.PDF - Robinson Helicopter Company Accident Report (item 4, .PDF, 9.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40458720&FileExtension=.PDF&FileName=Robinson%20Helicopter%20Company%20Accident%20Report-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 5, .PDF, 355 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40458721&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Master.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.