ERA10TA142

Incomplete clearing of snow from the helipad and vicinity. Contributing to the accident was the lack of a NOTAM regarding the presence of snow banks and the pilot's failure to ensure that the helicopter was clear of a snow bank prior to departure.

The hospital was equipped with two helipads; one at ground level and one on the rooftop. The rooftop pad had not been cleared of snow, and the flight was the first to arrive since the ground-level pad was cleared of snow the previous day. According to the pilot of the medical transport flight, while on final approach to the ground-level helipad, he observed that it was clear of snow, but that snow banks 2 to 5 feet high bounded the pad. The pilot intended to land facing a wall that was about 20 feet from the edge of the pad, while leaving sufficient room to allow the medical receiving personnel to safely maneuver themselves, their equipment, and their patients between the front of the helicopter and the snow bank. After the patients were unloaded and the helicopter was secured, the pilot and flight paramedic went into the hospital for about 12 minutes. On their return to the helicopter, the crew observed that the fenestron was in contact with the top of a snow bank. They examined the fenestron and tail rotor, determined that the helicopter was undamaged, and proceeded with boarding and departure activities. During the attempted liftoff, the pilot noticed a vibration from the rear of the aircraft. He lowered the collective, turned off the engine, and exited the helicopter to determine the cause of the vibration. The helicopter sustained damage to the fenestron, tail rotor blades, and tail rotor drive components due to contact with the snow bank. The hospital used its security and facilities personnel to clear snow from the helipads, but it did not possess or provide them with any formal guidance regarding snow-clearing procedures. Site documentation indicated that the helipad pavement was unmarked, with the exception of a 3-foot wide perimeter stripe. Although compliance was not mandatory, the snow removal was not accomplished in accordance with readily-available Federal Aviation Administration guidance. Snow bank heights and distances from the pad did not provide adequate clearances for operations; the pad pavement was not fully cleared, and the pad perimeter stripe behind the helicopter was completely obscured by a snow bank. The hospital did not issue a Notice to Airmen (NOTAM) regarding the presence of snow banks. The crew's pre-departure examination of the fenestron and tail rotor was superficial and unlikely to detect possible damage. No circumstances that precluded the crew from requesting the removal of additional snow, or rolling the helicopter forward so that the fenestron was clear of the snow bank prior to the attempted departure, were discovered. Examination of security video was inconclusive as to whether the damage was incurred during the arrival, the attempted departure, or both.

HISTORY OF FLIGHT On February 11, 2010, about 2236 Eastern Standard Time, a Eurocopter AS 365 N2, N61MD, operated by the Maryland State Police Aviation Command (MSPAC), was substantially damaged when it contacted a snow bank during operations on the ground-level helipad at Prince George's General Hospital (1MD4), Cheverly, Maryland. The commercial pilot and the pilot-rated flight paramedic were not injured. The public medical evacuation flight was being operated in night visual meteorological conditions, and no flight plan was filed. About 2112, the helicopter departed Andrews Air Force Base (ADW), Camp Springs, Maryland, under visual flight rules (VFR), in order to retrieve and transport two patients from an automobile accident site to 1MD4. The helicopter landed at the automobile accident site, the patients were loaded, and about 2200, the helicopter departed for 1MD4. While en route to 1MD4, the pilot was advised by hospital personnel to land on the ground-level helipad, due to the presence of ice on the hospital's elevated helipad. According to the pilot, due to noise abatement procedures and the reported winds at ADW, he approached 1MD4 from the south-southeast. He stated that when he was on final approach to the pad, he observed that it was clear of snow, but that it had snow banks around the perimeter. He also noted that a paved path was cleared of snow to allow the hospital receiving team to access the helipad from the hospital building. The pilot stated that during the final approach, he was concerned about creating "white out" conditions (blowing snow which would restrict visibility) as the helicopter neared the ground. In addition, he wanted to position the helicopter so that the clearance between the snow banks and the front of the helicopter would permit the hospital receiving team to maneuver around the helicopter. The pilot stated that "the approach was made to a high hover with straight let down," and that it "was completed to the center of the ground pad to ensure safe clearance for the hospital personnel to safely maneuver to unload the patients." The helicopter landed about 2212, facing slightly south of west. The pilot stated that "the landing...was accomplished with no incidents detected." After landing, the flight paramedic and the receiving team offloaded and transported the patients to the hospital emergency department, while the pilot shut down the helicopter. The pilot reported that the shutdown was normal, and that after he secured the helicopter, he joined the flight paramedic in the hospital. About 2229, when the pilot and flight paramedic returned to the helicopter, the pilot noticed that the aircraft's fenestron was resting on top of a snow bank that was approximately 3 feet high. He inspected the fenestron and did not detect any damage. According to the flight paramedic, he suggested to the pilot that it might be appropriate to remove some of the snow beneath the fenestron, in order to provide more clearance for the takeoff. The pilot determined that "since there was no damage" and that "the tail rotor itself was clear of the snow, a straight up take off with no yaw movement would be made." The engine start was completed, with no anomalies noted. About 2236, the pilot initiated "a slow deliberate takeoff," and when the helicopter "became light on the wheels, but prior to takeoff, a vibration was detected, emanating from the rear of the aircraft." In response to the vibration, the pilot lowered the collective, shut down both engines, and applied the rotor brake. The pilot stated that after he shut down and secured the helicopter, he and the flight paramedic visually inspected the helicopter. The pilot stated that the inspection revealed that "the fenestron was found to be severely damaged by the tail rotor blades, the right tail rotor gear box cap appeared to have been ingested by the tail rotor, and numerous tail rotor blades were damaged." Post accident examination by MSPAC and Federal Aviation Administration (FAA) personnel revealed substantial damage to the tail rotor blades, the fenestron, the tail rotor gear box, and its mounting structure and drive coupling. Some portions of the fenestron and other components in that area were of composite construction, of light-colored material. PERSONNEL INFORMATION FAA records indicated that the pilot held a commercial pilot certificate with rotorcraft helicopter and instrument helicopter ratings. His most recent FAA second-class medical certificate was issued in June 2009. The MSPAC reported that the pilot had 2,452 total hours of flight experience, including 360 hours in the accident helicopter make and model. He had 25 hours of flight experience in the accident helicopter make and model in the 90 days prior to the accident, and 6 hours in the 30 days prior to the accident. FAA records indicated that the flight paramedic held a private pilot certificate with multiple ratings, including rotorcraft helicopter. AIRCRAFT INFORMATION FAA records indicated that the helicopter was manufactured in 1993, and registered to the MSPAC in 1995. It was equipped with two Turbomeca Ariel turboshaft engines, a single main rotor system, and a shrouded tail rotor referred to as a "fenestron." The landing gear configuration was tricycle-style, with retractable wheel-and-tire gear. The overall color of the helicopter was dark brown or black. Manufacturer's published technical data indicated that the overall length of the helicopter, from the most-forward extent of the main rotor blade to the aft end of the fuselage, was 45.1 feet. The main rotor diameter was 39.2 feet, the fuselage length was 38.2 feet, the fenestron ground clearance was 2.2 feet, and the pilot's station was situated about 32 feet forward of the fenestron. Documentation provided by the MSPAC indicated that the helicopter was within applicable weight and balance limits for both its arrival at, and attempted departure from, the hospital helipad. METEOROLOGICAL INFORMATION The 2255 automated weather observation at ADW, located 7 miles south of 1MD4, recorded winds from 310 degrees at 9 knots, 10 miles visibility, clear skies, temperature -2 degrees C, dew point -7 degrees C, and an altimeter setting of 29.88 inches of mercury. HELIPORT INFORMATION FAA database information for 1MD4, which consisted of facility data provided by the hospital, indicated that the hospital was equipped with two separate helipads; one at ground level, designated "H1," and one on the hospital rooftop, designated "H2." According to the FAA and operator's databases, the ground-level pad was equipped with perimeter lights and a lighted wind indicator. The databases indicated that the pad was a square which measured 67 feet on each side. The databases indicated that the rooftop pad was a square that measured 40 feet per side. Helipad elevation was listed as 297 feet above mean sea level. The accident occurred on the ground-level pad. A north-south brick wall of the hospital structure was located about 20 feet west of the west edge of the paved pad surface. The paved surface was black in color, and was devoid of any markings except a perimeter stripe. A white stripe, approximately 3 feet wide, was painted around the entire perimeter of the pad; its outer edge was coincident with the outer edge of the pad pavement. Notices to Airmen (NOTAMs) obtained by the pilot prior to the flight included citations of snow banks at several local airports, but did not include warnings about snow banks at 1MD4. ADDITIONAL INFORMATION Hospital Surveillance Imagery A hospital surveillance camera that viewed the lower helipad recorded the arrival and attempted departure of the helicopter. The camera was situated west of the pad, and viewed the pad looking down and to the east. The imagery was reviewed to determine the sequence and timing of events, as well as possible details regarding the nature of the