NTSB Factual Report

***This report was modified on March 17, 2016. Please see the docket for this accident to view the original report.***

On August 4, 2015, about 2230 mountain daylight time, a MD Helicopters 369E, N43792, impacted Beaver Lake during water bucket operations four miles northwest of Whitefish, Montana. The helicopter became submerged in the lake. The commercial pilot sustained minor injuries. The helicopter was registered to Two Bear Air 2 LLC, Whitefish, Montana, and operated by the pilot under the provision of 14 Code of Federal Regulations Part 91 as a personal flight. Night visual meteorological conditions prevailed and no flight plan was filed. The flight originated from private property on Lion Mountain, Whitefish, Montana.

The pilot reported that he was hovering over a lake at night while practicing water bucket operations. He was using the helicopter's landing light and newly installed movable searchlight positioned to shine underneath and toward the left side of the helicopter for illumination. He reported that he was able to see the shoreline, horizon, and the texture on the water during these operations. During the third load, he reported that he was transitioning his sight "forward and inside to the instrument panel," and that while he was scanning the instrument panel, he "noticed the rotor disk dipping toward the water." He stated that he saw the main rotor blades strike the water and then the helicopter impacted the water. The cockpit filled with water as the helicopter rolled upside-down and began to sink. The pilot reported that while he was egressing from the cockpit underwater, he felt his "helmet tug backwards and I realized the communications cord was still attached to the helicopter." The pilot removed his helmet, surfaced, and swam to the shore without further incident. The recovery of the helicopter from the lake revealed substantial damage to the fuselage, the main rotor blade system, and the tail boom.

The pilot reported there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.

PERSONNEL INFORMATION

The pilot reported that he had prior formal external load training, but no formal over water external load training. He reported that he had never had formal underwater egress training. He also reported that he was not wearing a flotation device or carrying a self-contained breathing device during the over water flight.

AIRCRAFT INFORMATION

The helicopter did not have a flotation system installed at the time of the accident. The helicopter's manufacturer had optional emergency and utility flotation systems available for this helicopter.

The water bucket and suspension lines were directly connected to the cargo hook for the accident flight. The pilot suggested as a safety recommendation, to "increase length of attaching cable for external loads."

ADDITIONAL INFORMATION

Aviation Life Support Systems

The pilot was wearing an Evolution Helmets, LLC model 252 helmet during the flight. The helmet sustained no damage during the accident sequence. The helmet had a Bose Corporation A20 communications system installed. The Bose Corporation A20 Owner's Guide states in part; "Do not use the headset with a helmet or as part of a crash protection system. The headset is not intended for such use, and has not been certified for crash protection. Dismantling, reassembly, or modification of the headset, or any part, for use in a helmet or other crash protection system could result in severe bodily injury and such unauthorized use will void the limited product warranty."

The Federal Aviation Administration (FAA) has released Special Airworthiness Information Bulletin (SAIB) CE-16-08 concerning the use of noise cancelling headsets. The SAIB states in part:

"In many cases, pilots are using the noise cancelling headsets as supplementary equipment during operations. When wearing these headsets, the pilot may be unaware of environmental sounds and audible warning annunciations in the cockpit that do not come through the intercom system."

Additionally, the SAIB states:

"Become familiar with the safety information in FAA Information for Operators (InFO) 07001 and elect to find other solutions to discern such alarms or sounds, or discontinue using these headsets if any audible alarms or environmental sounds cannot be discerned while wearing a noise cancelling headset."

Currently, there are no federal or industry standards/requirements for helmet use in helicopters, or for helmet design and crashworthiness specifications when used in helicopters.

This model of helmet, with the Bose Corporation A20 system installed, did not have a quick disconnect assembly at the helmet, which would facilitate a clean break of the helmet from the intercom system (ICS) cord and the ICS receptacle.

The Transportation Safety Board of Canada has published an aviation safety advisory (2006) pertaining to the post-accident survivability of direct-to-airframe helicopter cord connections. The aviation safety advisory was based on a Messerschmitt-Bolkow-Blohm BO-105 accident (A05A0155) and states in part;

"After ditching or water impact, the occupants of a capsized helicopter are prone to disorientation. Therefore, unimpeded egress through any available exit is vital to survival. An attached communication cord that will not release cleanly may impede this egress."

MD Helicopters, Incorporated has released an operational safety notice, OSN2015-001 Helicopter Communication Cord Connection, and states in part;

"Use of an intermediate "pig-tail" communication cord can help to mitigate this safety hazard. Instead of plugging the helmet communication cord directly into the ICS receptacle, the helmet cord is instead plugged into one end of the intermediate cord, while the other end is plugged into the ICS receptacle. The helmet communication cord is then able to release cleanly from the intermediate cord receptacle as it is pulled in the direction of travel during egress."

Over Water Aviation Life Support Systems Requirements

14 Code of Federal Regulations (CFR) Part §91.205 Powered Civil Aircraft with Standard Category U.S. Airworthiness Certificates: Instrument and Equipment Requirements states in part;

"(12) If the aircraft is operated for hire over water and beyond power-off gliding distance from shore, approved flotation gear readily available to each occupant and, unless the aircraft is operating under part 121 of this subchapter, at least one pyrotechnic signaling device. As used in this section, "shore" means that area of the land adjacent to the water which is above the high water mark and excludes land areas which are intermittently under water."

§91.205 does not address helicopters that are operated for private use. Additionally, §91.205 does not specifically address operating off of or to water flights and hovering flights over water sources.

An example of a flight regulation that specifically addresses helicopters in these two modes of flight is the National Wildfire Coordinating Group's Interagency Helicopter Operations Guide (IHOG), last published in 2013. Chapter 9: Equipment Requirements and Maintenance, IV. Survival Equipment, A. Over Water Flotation and Survival Equipment, states in part;

"Approved Personal Flotation Devices (PFD). Shall be worn by each individual on board the helicopter when conducting opera­tions beyond gliding distance to shore, operating off of or to water and during all hovering flights over water sources such as ponds, streams, lakes, and coastal waters."

The FAA Helicopter Flying Handbook (FAA-H-8083-21A) does not address specific over water survival gear recommendations or requirements.

The FAA Helicopter Instructor's Handbook (FAA-H-8083-4) states for a flight instructor to, "discuss the requirements" of 14 CFR Part §91.205. However, there are no specific over water survival gear recommendations or requirements listed.

FAA Advisory Circular 120-47 Survival Equipment for Use in Over Water Operations was last published in 1987. While not regulatory in nature, this document addresses some recommended over water survival equipment.

Over Water Operations

The U.S. Army has published Field Manual 3-04.203 Fundamentals of Flight (2007). This manual provides information on over water flight operations for helicopters. This manual states in part;

3-190. Conducting flight in over water operations usually includes lack of visible horizon due to overcast skies, restricted visibility, difficulty in detecting altitude above water, water spray coating the windscreen, and the potential for spatial disorientation.

4-138. Water is the most difficult surface over which to hover as it is nearly absent of visual reference points. If possible, the aircraft should be maneuvered near some object, such as a tree stump, ChemLight, or buoy, to provide a reference point. If waves are present, the aviator tends to move laterally with the waves. Accurate height estimation requires use of a radar altimeter when hovering over water.

NTSB Probable Cause

The pilot’s failure to maintain altitude and a level attitude while hovering over water at night during an external load operation, which resulted in the helicopter’s main rotor contacting the surface of the water.