Recall the accident of N101BX in May 2008.

http://www.ntsb.gov/ntsb/brief.asp?ev_id=20080609X00814&key=1

I'm guessing that there was an ice induced tail stall.  I note that one winglet was found 4000 ft away from the weckage, and this supports that the winglet departed the airframe early in the process.

A friend has asked if the departure of one winglet would cause uncontrolled flight, since warmer above freezing temperatures were found below 14,000'.  I can't believe that this alone would cause serious control problems.

Any comments from experienced pilots and engineers?

Jeff Liegner

LIVP

NTSB Identification: NYC08LA176
14 CFR Part 91: General Aviation
Accident occurred Thursday, May 08, 2008 in Snow Hill, NC

Aircraft: Desalvatore Al Lancair IV-P, registration: N101BX
Injuries: 2 Fatal.

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.

On May 8, 2008, at 1310 eastern daylight time, an amateur-built Lancair IV-P, N101BX, was destroyed when it impacted terrain following an uncontrolled descent near Snow Hill, North Carolina. The certificated commercial pilot and passenger were fatally injured. Visual meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan was filed and activated for the personal flight. The flight originated at Page Field (FMY), Fort Myers, Florida, and was destined for Hartford-Brainard Airport (HFD), Hartford, Connecticut. The flight was conducted under 14 Code of Federal Regulations Part 91.

According to preliminary information provided by the Federal Aviation Administration (FAA), the pilot departed FMY under visual flight rules about 1030. While enroute, the pilot contacted air traffic control (ATC) and requested visual flight rules flight following services. He later requested, and was given, an IFR clearance. While flying at 17,000 feet, shortly before the accident, the pilot requested to descend due to icing conditions. The pilot was cleared to descend to 15,000 feet. The final radar target was observed about 2 miles southwest of the accident site at 15,000 feet.

The crew of a Beech 400 was in contact with ATC, and was flying in the area of the accident airplane. Both the captain and first officer provided similar written statements recounting what they heard and observed. The crew was initially cleared to climb to 15,000 feet, but was later told to stop their climb at 14,000 feet because a Lancair, the accident airplane, was descending from 17,000 feet to 15,000 feet due to icing. Upon reaching 14,000 feet, the crew observed a target on their traffic alert and collision avoidance system (TCAS) that was about 1,000 feet above them in altitude, at their 12 o'clock position, and at a distance about 7 to 8 miles. The next update of the TCAS showed the traffic at the same altitude, still at the 12 o'clock position, and at a distance about 5 to 6 miles. The crew questioned ATC if this was the traffic that they had previously been alerted to, which was answered in the affirmative.

The next time the crew looked at the TCAS, the traffic was 2,000 feet below them, at the 2 to 3 o'clock position, and a distance of 4 miles. The crew did not observe any further TCAS updates of the traffic, and shortly thereafter the crew briefly heard the sound of an emergency locator transmitter in the background of the controller's transmission.

Additionally, the crew reported that they were in instrument meteorological conditions at the time of the event, and that while flying at 14,000 feet, there was no icing present. They were not sure of the outside air temperature, but they remembered that the ram air temperature was over 10 degrees Celsius.

The airplane was examined at the accident scene by Federal Aviation Administration (FAA) inspectors. According to the inspectors, the entirety of the wreckage was accounted for at the scene, with the exception of one winglet, which was found on the roof of a house about 4,000 feet from the main wreckage. The majority of the wreckage was consumed by a post-impact fire. Control continuity was established from the cockpit area to each of the flight control surfaces.

The engine was transported to a recovery facility, where it was further examined by a Safety Board investigator and a representative of the engine manufacturer.

The engine was intact, with all of the accessories attached, with the exception of the fuel pump. Two of the four propeller blades were separated from the propeller hub, one blade was broken in half, and the fourth blade was undamaged. The aft portion of the engine was fire damaged, and the oil sump was crushed upward into the camshaft. Borescope examination of all cylinders revealed that the piston heads and cylinder domes did not exhibit any abnormal combustion deposits. Rotation of the crankshaft at the propeller confirmed valve train continuity, and compression was confirmed on all cylinders. Both turbochargers were fire- and impact-damaged, and neither of their driveshafts was free to rotate.

The top six spark plugs were removed, and examination revealed that they exhibited light gray deposits in the electrode areas. The fuel pump was separated from the rear of the engine, and was coated with soot. The drive coupling was intact, but the drive shaft was not free to rotate. Further disassembly revealed that the interior was dry and heat discolored. No internal mechanical damage was observed. Disassembly and examination of the fuel manifold revealed that the fuel screen was absent of debris and fuel. The oil filter was fire- and impact-damaged. Examination of the paper element revealed that it was charred, but no metal particles were observed.

The pilot held a commercial pilot certificate with ratings for airplane single and multi-engine land, and instrument airplane.

The weather conditions reported at Goldsboro-Wayne Municipal Airport (GWW), Goldsboro, North Carolina, located about 9 nautical miles west of the accident site, at 1320, included winds from 210 degrees at 5 knots, 7 statute miles visibility in light rain, scattered clouds at 600, 1,700, and 7,000 feet, temperature 70 degrees Fahrenheit (F), dewpoint 64 degrees F, and altimeter setting of 29.93 inches of mercury.