N718PPPiel Emeraude CP-301A · 1963

On March 15, 2012, about 1255 central daylight time, an experimental amateur-built Emeraude CP-301-A, N718PP, was destroyed when it impacted trees and terrain while returning to Ruckel Airport (FL17), Niceville, Florida. The two airline transport pilots were fatally injured. Visual meteorological conditions prevailed. No flight plan had been filed for the personal flight to Yellow River Airstrip (FD93), Holt, Florida, which was conducted under the provisions of 14 Code of Federal Regulations Part 91.

According to the responding Federal Aviation Administration (FAA) inspector, one of the pilots, who was also the owner of the airplane, had previously lost his FAA medical certificate due to injuries sustained in an earlier accident, and was about 2 weeks from qualifying for a new one. The pilot/owner, who was not the airplane's original builder, had intended to fly it to FD93 to undergo a condition inspection, but needed the other pilot onboard to act as pilot in command.

The inspector also reported that the mechanic who was going to do the condition inspection stated that when the pilot/owner contacted him, he did not express any concerns about the airworthiness of the airplane.

According to statement by an air traffic control specialist at nearby Eglin Air Force Base, about 1250, he received a transmission from the airplane that it had just departed from FL17 [as was the custom for airplanes from that airport.] The controller then attempted to contact the airplane twice to determine the pilot's intentions, but received no response. The controller did not recall seeing a primary (skin paint) radar return at the time.

An air traffic supervisor at Eglin reported that a playback of radar data indicated brief primary radar contact with the airplane, but no track or altitude could be ascertained.

According to a witness who was at the north end of the takeoff runway on the west side, the airplane took off heading north. When the airplane was about halfway down, and about 300 to 400 feet above the runway, the witness heard a power reduction. The airplane did not turn to return to the runway, but continued straight ahead over trees, and the witness eventually lost the sound of the engine. A few minutes later, the witness heard the sound of sirens.

Another witness, who lived near FD93 and was accustomed to seeing airplanes, stated that he was driving southbound on route 285 northwest of the FL17, and about ¼ mile north of the new bypass interchange, when he saw the airplane from the side, about ½ mile away, with the propeller stopped. The wings were level, the airplane was descending at an angle of about 45 degrees, and he thought that the airplane was gliding into FL17, but lost sight of it behind trees.

The pilot/owner of the airplane, age 59, held an airline transport pilot certificate with ratings for single engine land and multi-engine land airplanes. The pilot's computer logbook indicated 8,549 total flight hours, but did not break down hours into single engine or multi-engine time. The pilot was also a retired U.S. Air Force and former corporate pilot, and had previously built and flown an Avid Flyer

On June 9, 2008, the pilot/owner was involved in an accident with the Avid Flyer, NTSB identification number NYC08FA211, that resulted in traumatic brain injuries. FAA records indicated that the pilot/owner had subsequently been denied medical certificates, but according to his wife, he was having the airplane inspected in anticipation of a favorable outcome from his latest request.

The pilot in command, age 66, held an airline transport pilot certificate with ratings for single engine land, single engine sea, and multi-engine land airplanes, and rotorcraft-helicopter. He also held flight instructor and mechanic certificates. On his latest FAA first class medical certificate application, the pilot reported 2,500 hours of civilian flight time. According to the pilot's wife, his logbook was on a computer that no longer functioned, but during his 27 years in the U.S. Navy, including his time a carrier air group commander, his wife estimated that he had flown 4,000 to 5,000 hours. The pilot's wife also stated that the reason he was onboard the airplane was because the pilot/owner could not legally fly it solo until he received medical approval from the FAA.

FAA records indicated that the airplane was first registered to the pilot/owner on March 29, 2011. Photographs of partially charred logbook records indicated that the latest condition inspection (required yearly of experimental aircraft; certified aircraft undergo annual inspections) occurred on January 21, 2011.

The airplane was powered by a Continental O-200-A engine.

According to the pilot/owner's wife, he did not fly the airplane while waiting for his medical situation to resolve, but did start and taxi it around. She also noted that the previous owner had hangared the airplane at another airport in north Okaloosa County when they bought it. A mechanic fixed some items and completed a condition inspection, then the previous owner flew it to FL17. From what the pilot/owner's wife understood from her husband, the pilot in command had flown the airplane when it was hangared at the other airport, but had not flown it since it was relocated to FL17.

Weather, recorded at an air force base about 5 nm to the southwest, at 1256, included scattered clouds at 5,000 feet, a broken cloud layer at 20,000 feet, wind from 140 degrees true at 6 knots, visibility 10 statute miles, temperature 28 degrees C (82 degrees F), dew point 18 degrees C (64 degrees F), and an altimeter setting of 30.24 inches Hg.

According to an Okaloosa County Sheriff's Office report, the wreckage was located in the vicinity of 30 degrees, 32.244 minutes north latitude, 086 degrees, 26.178 minutes west longitude, or about ½ nautical mile, 010 degrees magnetic from the threshold of FL17 runway 18. Upon arrival at the scene, deputies found the airplane on fire, and that both pilots and the engine were located about 60 to 80 feet forward of the main wreckage.

The FAA inspector and a representative from the engine manufacturer documented the accident scene. The wreckage path, which was oriented along a heading about 080 degrees magnetic, began in tree tops about 15 feet above the ground, about 30 feet before an initial ground impact point, and 75 feet prior to where the main wreckage came to rest. The FAA inspector also noted that the trees receiving the initial strikes did not extend up beyond the other trees, and that the initial strikes from both wings were at the same height, consistent with a wings-level attitude at the time.

All flight control surfaces were accounted for at the accident site. Control cable continuity was established from the cockpit to the control surfaces in the tail. Control tubes to the ailerons were separated from their respective mounting locations and exhibited signatures consistent with overload.

The engine was still attached to the firewall, and both were found separated from the main wreckage. The engine crankshaft was rotated to confirm continuity. Each of the four piston cylinders was borescoped with no anomalies noted. Thermal damage and melting precluded further documentation of the accessory section, the carburetor, the left magneto and the ignition leads. The right magneto could not be rotated. A photograph of the exhaust system revealed malleable bending.

Photographs by the engine manufacturer representative of the upper spark plugs indicated dark coloring. The representative did not remove the lower spark plugs, but did a borescope examination of the engine cylinders, with no anomalies noted. Coloring of the lower spark plugs was not documented, and the representative has since left the company.

The position of the carburetor heat handle was not noted during the on-scene examination, and could not be determined from photographs.

Photographs of the fixed pitch, two-bladed metal propeller revealed that it remained attached to the crankshaft flange. One blade and exhibited twisting and bending in addition to chordwise scratching and polishing, consistent with the presence of power, while the other blade was bent aft about 1/3 of the way from the tip.

A checklist found between the pilot/owner and the main wreckage was open to the page titled, "Engine Failure after Takeoff." The pilot/owner's wife, who had flown with him on many occasions, recalled that he normally did wear a kneeboard, but could not recall if he normally took off with it with any particular page or procedure open.

When plotted on Google Earth, the position of the wreckage was about 540 feet north of a new east-west bypass that was under construction, and about 1,400 feet south of a large sod field. Heading south, toward FL17, would have brought the airplane into a heavier stand of trees than those on the easterly heading. In addition, there was an open construction area commencing about 240 feet southeast of the crash site.

Autopsies were performed on both pilots by the Florida District 1 Medical Examiner Office, Pensacola, Florida, with cause of death for both pilots determined to be "multiple blunt force injuries." Toxicological testing was subsequently performed at the FAA Bioaeronautical Research Laboratory, Oklahoma City, Oklahoma, with no anomalies noted for either pilot.

FAA Advisory Circular 20-113, "Pilot Precautions and Procedures to be Taken in Preventing Aircraft Reciprocating Engine Induction System and Fuel System Icing Problems," includes several carburetor icing considerations:

"Throttle Ice - Throttle ice is usually formed at or near a partially closed throttle, typical of an off-idle or cruise power setting. This occurs when water vapor in the air condenses and freezes because of the cooling restriction caused by the carburetor venturi and the throttle butterfly valve. The rate of ice accretion within and immediately downstream from the carburetor venturi and throttle butterfly valve is a function of the amount of entrained moisture in the air. If this icing condition is allowed to continue, the ice may build up until it effectively throttles the engine. Visible moisture in the air is not necessary for this type icing, sometimes making it difficult for the pilot to believe unless he is fully aware of this icing effect. The effect of throttle icing is a progressive decline in the power delivered by the engine. With a fixed pitch propeller this is evidenced by a loss in engine RPM and a loss of altitude or airspeed unless the throttle is slowly advanced. With a constant speed propeller, there will normally be no change in RPM but the same decrease in airplane performance will occur. A decrease in manifold pressure or exhaust gas temperature will occur before any noticeable decrease in engine and airplane performance. If these indications are not noted by the pilot and no corrective action is taken, the decline in engine power will probably continue progressively until it becomes necessary to retrim to maintain altitude; and engine roughness will occur probably followed by backfiring. Beyond this stage, insufficient power may be available to maintain flight; and complete stoppage may occur, especially if the throttle is moved abruptly.

Fuel Vaporization Ice - This icing condition usually occurs in conjunction with throttle icing. It is most prevalent with conventional float type carburetors, and to a lesser degree with pressure carburetors when the air/fuel mixture reaches a freezing temperature as a result of the cooling of the mixture during the expansion process that takes place between the carburetor and engine manifold. This does not present a problem on systems which inject fuel at a location beyond which the passages are kept warm by engine heat. Thus the injection of fuel directly into each cylinder, or air heated by a supercharger, generally precludes such icing. Vaporization icing may occur at temperatures from 32 degrees F. to as high as 100 degrees F. with a relative humidity of 50 percent or above. Relative humidity relates the actual water vapor present to that which could be present. Therefore, temperature largely determines the maximum amount of water vapor air can hold. Since aviation weather reports normally include air temperature and dew point temperature, it is possible to relate the temperature – dew point spread to relative humidity. As the spread becomes less, relative humidity increases and becomes 100% when temperature and dew point are the same. In general, when the temperature-dew point spread reaches 20° F. or less, you have a relative humidity of 50 percent or higher and are in potential icing conditions.

The pilot should remember that induction system icing is possible, particularly with float type carburetors, with temperatures as high as 100 degrees F and the humidity as low as 50 percent. It is more likely, however, with temperatures below 70 degrees F and the relative humidity above 80 percent. The likelihood of icing increases as the temperature decreases (down to 32 degrees F) and as the relative humidity increases."

Multiple examples of carburetor icing probability charts exist. Probability of carburetor icing is typically broken down into several categories, from least to most: no probability, light (on some charts) icing at glide and cruise power, serious icing at glide power, serious icing at cruise power, and icing for pressure-type carburetors.

When ambient temperature and dew point were plotted on a chart found in FAA Advisory Circular FAA - P - 8740-24 "Tips on Winter Flying," the results indicated a probability of light carburetor icing at glide or cruise power.

When ambient temperature and dew point were plotted on chart found in FAA Special Airworthiness Information Bulletin CE-09-35, "Carburetor Icing Prevention," the results indicated a probability serious icing at glide power.

When the ambient temperature and dew point were plotted on other available charts, many of which were based on a 1970 "Fuels and Lubricants of the National Research Council of Canada" study, the results were similar to those of CE-09-35. The charts also graphically indicated that under certain conditions, carburetor icing could occur in as low as 20 per cent relative humidity.

A copy of the airplane's pilot's operating handbook was not available. However, a checklist found for another CP-301 indicated that during engine run-up, the pilot was to "select full carburetor heat and check for operation" and for takeoff, "carburetor air cold – fully in."