14 CFR Part 91: General Aviation
Accident occurred Saturday, March 08, 2014 in Fairhope, AL
Probable Cause Approval Date: 06/22/2015
Aircraft: CESSNA 172D, registration: N2755U
Injuries: 1 Serious.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The pilot reported that the airplane entered the downwind leg of the traffic pattern behind a large helicopter and that he followed the helicopter closely in the traffic pattern. While on short final approach, the airplane remained behind the helicopter as the helicopter was terminating its approach about three-quarters down the runway. When the airplane was about 30 ft above the approach end of the runway, it banked and pitched suddenly, and it then impacted the ground. The pilot reported no mechanical malfunctions or failures with the airplane that would have precluded normal operation nor were any found during a postaccident examination of the wreckage. A simulation modeling the helicopter’s trailing vortex-generating tendencies showed that vortices of significant strength were likely present at the airplane’s reported position at the time of the upset. If the pilot had maintained adequate separation from the large helicopter during the approach to landing, the airplane likely would not have encountered the trailing vortices that caused the loss of airplane control.
The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The pilot’s failure to maintain adequate separation from a helicopter during the approach to landing, which resulted in an encounter with the helicopter’s trailing vortices, a loss of airplane control, and impact with terrain.
HISTORY OF FLIGHT
On March 8, 2014, about 1400 central standard time, a Cessna 172D airplane, N2755U, was destroyed when it impacted terrain while attempting to land at H L Sonny Callahan Airport (CQF), Fairhope, Alabama. The private pilot sustained serious injuries. Visual meteorological conditions prevailed , and no flight plan was filed for flight , which originated from Ferguson Airport (82J), Pensacola, Florida and was destined for CQF. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91.
The pilot was returning to CQF after completing youth introductory flights at 82J. The enroute portion of the flight was uneventful, and upon arriving in the vicinity of CQF, the pilot entered the downwind leg of the traffic pattern for runway 19. While on the downwind leg of the traffic pattern the pilot observed a large helicopter that was approaching the airport and was "almost on the ground." As the pilot was on the short final leg of the approach to the runway, at an altitude of about 30 feet agl, he noted that the helicopter was flying over the runway's parallel taxiway at about the mid-field point. Once the airplane reached the approach end of the runway the pilot observed the helicopter just past the mid-field point of the runway. About that time, one of the airplane's wings "went straight up," which is the last thing the pilot remembered about the flight. The pilot reported that prior to the upset, there were no mechanical malfunctions or other anomalies of the airplane that would have precluded normal operation
According to witnesses, the accident airplane was following the large helicopter in the airport traffic pattern. While on final approach, the accident airplane appeared to be "way too close" to the helicopter and was observed performing S turn maneuvers. The pilot of the helicopter then made a radio call to announce that he was going to fly to the south end of the field in a hover. While the helicopter was still in forward flight over the runway, the airplane reached the approach end of the runway and, at an approximate altitude of 30 feet above ground level (agl), the airplane suddenly rolled into a right wing low attitude followed by a left wing low attitude. The airplane then leveled out, impacted the ground in a level attitude forward of the runway threshold and a post impact fire ensued near the engine cowling. A witness reported that the large helicopter was "50 ft above the ground" when the accident airplane was upset.
According to the pilot of the helicopter, following an initial low approach to the runway that terminated in a hover, the co-pilot maneuvered the helicopter around the traffic pattern for a second landing. The crew observed the accident airplane while it was on the downwind leg of its approach, and commented that the airplane seemed to be flying closer than customary to the runway and the helicopter. The pilot subsequently advised the copilot to stop his descent at an altitude of between 300 and 500 feet agl, and commence his final landing approach further down the runway. As the helicopter continued its final descent, this time about 3/4 down the runway the crew heard via radio that the accident airplane had crashed.
WRECKAGE AND IMPACT INFORMATION
The airframe and engine were examined at the accident site by representatives of the airframe and engine manufacturers under the supervision of a Federal Aviation Administration inspector. The initial impact point was slightly forward of the runway 19 numbers and the main wreckage was located 800 feet past the initial impact point and 50 feet west of the runway edge. Abrasions of the runway surface consisting of brake rotor scars and propeller strikes were traced from the initial impact point to the location of the main wreckage.
The cabin, tailcone, and wing roots exhibited signs of thermal damage. All flight control surfaces remained attached to their respective airframe components, and flight control continuity was traced from each flight control surface to the cockpit. The flap handle was observed in the retracted position and due to post-crash fire the flap setting could not be determined at the accident site. The elevator trim actuator was in the neutral position, but the elevator trim indicator could not be examined due to fire damage. The fuel system was also damaged from the post-crash fire and could not be examined. Both propeller blades remained attached to the hub, which was found attached to the crankshaft. One blade displayed thermal damage and twisting. The other blade was separated at the tip and exhibited chordwise scoring and curling.
There was significant fire and impact damage to the engine. The carburetor separated from the engine and was melted by postcrash fire. Both magnetos remained attached to the crankcase. All spark plugs contained varying amount of thermal and impact damage, but also remained installed on the engine.
The top spark plugs were removed and examined, with all exhibiting normal wear signatures. The bottom spark plugs were inspected with a borescope and no anomalies were noted. The magnetos exhibited significant thermal damage; one magneto could not be rotated by hand and the other magneto was rotated, but did not produce a spark. Both magnetos were disassembled and no abnormalities were noted.
The cylinders were examined using a borescope. The pistons and cylinder bores exhibited signs of normal combustion and all of the valve faces and seats were in place. The crankshaft was rotated at the propeller flange, and thumb compression was confirmed on each of the six cylinders. All rocker arms and valves operated normally during crankshaft rotation. Valvetrain continuity was confirmed on all of the cylinders and to the accessory drive gears.
The oil screen was found on the runway about halfway between the initial impact point and the main wreckage. The screen did not contain any contaminates.
PERSONNEL INFORMATION
The pilot held a private pilot certificate with a rating for airplane single engine land. He had accumulated about 633 total hours of flight time, of which 173 hours were in the accident airplane make and model.
METEOROLOGICAL INFORMATION
The 2000 recorded weather observation at the MBLA1 buoy, located 7 nautical miles southeast of the accident site, included wind from 120 degrees at 5 knots, temperature 15 degrees C, and an altimeter setting of 30.15 inches of mercury.
Two witnesses reported winds at the time of the accident at CQF were from the south straight down the runway at approximately 5-7 knots.
AIRPORT INFORMATION
The single asphalt runway at CQF was 6,604 feet long by 100 feet wide and was configured in a 1/19 orientation. A parallel taxiway spanning the full length of the runway was present on the west side of the runway. The airport was not served by a local air traffic control tower.
ADDITIONAL INFORMATION
Rotorcraft Trailing Vortices
The flight profile of the large helicopter, a CH-53E, provided by the helicopter pilot was sent to Sikorsky Aircraft Corporation and a proprietary analysis was conducted to examine the trailing vortex dissipation of the helicopter. The data, which included a heading of 190 degrees magnetic, 80 knots airspeed, altitude of 400 ft. agl, and a gross weight of 48,100 lbs. were programmed in a simulation. Data points for the blade radius and tip vortex core radius were then estimated and two videos were produced. One video was used to simulate 5 knot winds out of the southeast and another video was used to simulate a no wind scenario.
The wake evolution simulation was modeled as an unsteady two-dimensional vortex interaction problem. A differential equation was used to update the tip vortex position given its initial position and strength, which then produced the vortex trajectory. The helicopter heading and wind direction were used to map the two-dimensional wake to three dimensions including the runway position.
The results of both simulations showed a main rotor blade wind velocity of 60 knots. The simulations assumed the accident airplane trailed about 30 seconds (+/- 6 seconds) behind the helicopter. The study found that based on the airplane's altitude, the helicopter would need to be less than 200 ft above the ground for a vortex interaction to occur. A similar outcome would be expected for winds aligned with the runway heading at a velocity of 0 knots.
Given the weather conditions at the time of the accident, along with the gross weight of the helicopter, the analysis concluded that trailing vortices were likely present over the approach end of the runway at the time of the accident.
FAA Aeronautical Information Manual, Helicopter Trailing Vortices
According to the FAA's Aeronautical Information Manual, section 7-3-7:
"In forward flight, departing or landing helicopters produce a pair of strong, high-speed trailing vortices similar to wing tip vortices of larger fixed wing aircraft. Pilots of small aircraft should use caution when operating behind or crossing behind landing and departing helicopters."
http://registry.faa.gov/N2755U
NTSB Identification: ERA14LA147
14 CFR Part 91: General Aviation
Accident occurred Saturday, March 08, 2014 in Fairhope, AL
Aircraft: CESSNA 172D, registration: N2755U
Injuries: 1 Serious.
This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
On March 8, 2014, about 1400 eastern standard time, a Cessna 172D airplane, N2755U, operated by Gone Broke, LLC, was destroyed during a landing attempt and postcrash fire at H L Sonny Callahan Airport (CQF), Fairhope, Alabama. The private pilot sustained serious injuries. Visual meteorological conditions prevailed and no flight plan was file for the personal flight operating under the provisions of Title 14 Code of Federal Regulations Part 91. The flight was operating under visual flight rules. The departure time and location have not been determined.
According to several witnesses, a military helicopter had been operating in the pattern at CQF for about 10 minutes. During the maneuver the helicopter descended into a hover over the approach end of runway 19, then transitioned into a takeoff and entered an initial climb about mid field. While the helicopter was ascending, the Cessna 172D was attempting to land on runway 19. A witness reported the airplane was about 30 feet above ground level when it suddenly rolled right in a right wing low attitude, leveled out and then impacted the ground flat in a level attitude forward of the runway threshold. Subsequently a post impact fire ensued near the engine cowling.
According to a Federal Aviation Administration inspector, the airplane departed the right side of the runway and came to rest in the grass about 800 feet past the initial impact point and 50 feet west of the runway edge.
Postaccident examination of the airplane and engine by the FAA and airframe and engine manufacturers did not reveal any anomalies or malfunctions that would have precluded normal operation.
FAIRHOPE, Alabama -- A small plane crashed Saturday at H.L. Sonny Callahan Airport in Fairhope, sending one man to a local hospital.
The crash was reported around 2 p.m. when emergency medical responders were dispatched to the scene. The man who was flying the small Cessna has not yet been identified.
Officials said the Fairhope Volunteer Fire Department was still on scene around 3:30 p.m. The man was taken by Life Flight to USA Medical Center. A hospital official confirmed someone matching the description of the pilot arrived in their emergency room around 4:25 p.m.
Fire Chief Chris Ellis said the pilot was found outside of the plane when first responders arrived. A crew of about 20 firefighters were need to extinguish the blaze.
Only a portion of the plane’s fuselage, tail and cockpit were all that remained of the wreckage, Ellis said. It is unknown what caused the plane to catch fire, or whether the man was taking off or landing during the incident.
Ellis said he did not appear to have any life-threatening injuries.
As of late Saturday, no inbound flights are being allowed into the airport, Ellis said. Investigators with the Federal Aviation Administration will be on scene early Sunday to inspect the site.
This report has been updated to include comments from Fairhope Fire Chief Chris Ellis and a USA Medical Center official on Saturday March 8,2014 at 5:25 p.m.
Officials say a Cessna crashed at the Sonny Callahan Airport in Fairhope just after 2:00 pm today.
The airplane crashed upon landing and the pilot was trapped inside. He was pulled to safety by airport employees and a state agency official just before the plan caught fire.
The pilot, whose name has not yet been released, was lifeflighted to USA Medical Center but officials say he is expected to be ok.
FAIRHOPE, Ala. (WPMI) A fund has been opened to help the family of a pilot who was seriously injured in a plane crash earlier this month.
Roger James was flying the single engine Cessna plane March 8 when it went down and burst into flames in Fairhope.
The NTSB’s preliminary report says an investigation revealed no malfunctions with the aircraft of the engine.
