Aviation Accident Case Studies

DVI has investigated hundreds of aviation related accidents, failures, and calamities. DVI's Aviation Experts always provide independent and unbiased analysis regardless if we are working for the defendants, plaintiffs, insurance carriers, manufacturers, or other such clients. Our investigations are based upon the use of scientific methodologies, physical and factual evidence, and industry best practices. DVI's clients can count on our Aviation Experts to be available to tackle problems anywhere in the world, 24- hours a day, 7 days a week. Selected below are some of the types of cases that DVI's Aviation Experts have been a part of.   

Reconstructing Ground Vehicle Incidents

A ground support vehicle accidentally moved and pinching a ramp worker between the vehicle and a regional jet. DVI’s Aviation Experts were retained to investigate the accident and determine the cause of the unintended vehicle movement. Our investigators are not only trained as accident reconstructionists, but are also licensed aircraft and automotive mechanics. The subject vehicle’s throttle control, brake system, and shift control mechanisms were examined, including verification that all manufactures service recalls were performed. Full scale testing of the subject vehicle was performed using a data acquisition system and accelerometers, along with video documentation to create demonstrative evidence. DVI provided the client with expert opinions based upon scientific evidence and testing data.


Explaining How Cockpit Controls Are Designed

A student pilot, on his first solo cross country flight, inadvertently pulls the fuel shutoff control knob while reaching for what he believes to be the cabin heater control. Confused as to why the engine shutoff, the student decides to make an emergency landing in an open field and sustains serious back injuries. DVI was retained to investigate the accident, on behalf of the flight school that provided the student the training. DVI’s Pilot and Human Factor Experts were uniquely qualified to assist in the case, because our real world experience includes providing all levels of flight training, and teaching graduate level courses in Aviation Human Factors. DVI evaluated the wreckage deformation, training records, radar plots, and made measurements on several exemplar aircraft. Cockpit controls are designed based upon Human Factor principles. Control such as the fuel cutoff and heater can be coded for pilot recognition in various ways, to include shape, size, color, labeling, and type movement. DVI’s Aviation Experts provided opinions describing how controls can be differentiated, and how pilots are trained to deal with emergency situations. 


Evaluating Aircraft Maintenance Procedures

An aircraft maintenance facility performed a top overhaul on an aircraft, replacing all 6 cylinder assemblies. The work was supervised by a certificated aircraft mechanic, but performed by an “apprentice” mechanic. Shortly after the work was performed, a cylinder departed the engine while in flight, and the aircraft was forced to make an emergency landing. DVI has on staff certified aircraft mechanics (A&P) that also have FAA Inspection Authorization (IA) privileges. DVI's Aircraft Maintenance Expert performed a comprehensive wreckage examination, reviewed maintenance records, manufacture’s maintenance manuals, and evaluated the procedures used by the maintenance shop while performing work. DVI provided expert opinions based upon physical evidence found in the wreckage examination, which correlated to improper maintenance procedures, which explained the reasons for the cylinder departing the engine in flight.


Examining a Fractured Crankcase Thru-bolt 

An aircraft owner purchased an engine from a salvage yard, and had it field overhauled. During the overhaul the mechanic converted the engine from one model to another, but does not annotate the engine data plate. During annual inspections nuts are consistently found to be loose, including the prop to crankshaft flange attachment. Ultimately, the number two cylinder departs the engine in flight, and the pilot makes a successful off field landing without injury. DVI’s Material Science Expert was retained to examine the cylinder base studs and thru-bolts that failed. DVI discovered that incorrect and mismatched connecting rods were installed, incorrect cylinder base nuts were installed, and the prop STC was not approved for the original engine model number. Examination of the failed bolts was found to be consistent with a fatigue failure associated with a loss of pre-load. Fretting found on many other surfaces also suggested that a gradual loss of pre-load could have been occurring due to the excessive vibrations created by improperly balanced crankshaft and unapproved propeller installation. 


Analyzing a Weld Failure on an Exhaust Manifold

A certified aircraft was destroyed during an on-ground fire following an emergency descent and landing due to an in-flight fire. The left exhaust stack assembly contained an approximately four-inch fracture around the main collector welded joint. The left exhaust stack assembly was manufactured by an after market company that reverse engineered an OEM part and obtained an STC. DVI’s Aviation Experts examined the wreckage, and made a comparison between the aftermarket part and the OEM. The design of the OEM exhaust stack assembly was found to differ significantly from the comparable aftermarket, and was inadequate to carry the load of the turbocharger attached to the manifold. The weld fatigued and failed due to the unintended bending stresses. 


Explaining an Aircraft Mechanic’s Eye Injury

A regional airline mechanic was troubleshooting a claim by passengers that smoke was coming up from the floor during the flight. Under the floor there are two air conditioning packages or "packs" for air conditioning and pressurization. Each distribution system has fans and filters in the recirculation ducting to clean and condition the air. To troubleshoot the issue, the mechanic removed the floor access panels and activated the air-conditioning units. While observing the operation of the packs, the mechanic’s eyes were exposed to a smoke containing super heated particles. DVI’s Aircraft Maintenance Expert evaluated the maintenance protocols of the maintenance shop and evaluated the failed pack. It was determined the mechanic ignored safety protocols and was not wearing eye protection, and that the fan motor brushes were found to be 500 hours over the required Time Between Overhaul (TBO). The super heated particles were created by the failing motor brushes, and were being dispersed by the motor fans within the floor cavity. 


Determining Cockpit Visibility

An experienced flight crew was taxing out to a runway and struck a large and easily noticeable construction vehicle adjacent to the taxiway. At the time of the accident the aircraft was on the taxiway centerline, and should have been guaranteed taxiway clearances. DVI’s Aviation Human Factors Expert evaluated the cockpit visibility and issues concerning perceptional blindness. Perceptional blindness explains why an aircrews might only pay attention to a small subset of the stimuli to which they are exposed, and perceptual filtering is the process of past experience influencing what is or is not processed. In this instance, the aircrew taxied out on the centerline while simultaneously completing their pre-takeoff checklist, just like they have for thousands of times before. Because their past experiences dominated their perception of what should never be on the taxiway, they never registered or reacted to an unforeseen object in their path.


Departure from Controlled Flight

During the initial climb out after departure on an instrument flight, radio contact was lost after the pilot reported that he had a "prob"; the pilot did not state what problem he was experiencing. Attempts by the Air Traffic Controller to establish radio contact failed; radar contact was never established. No further radio contact was recorded with the flight nor did the flight arrive at the destination airport. A day later, an air and ground search team located the wreckage. DVI’s Aviation Experts were retained by the manufacture of one the aircraft’s primary instruments. DVI’s Experts was able to accurately reconstruct the accident and determine that the instrument had not failed in flight, and was not the cause of the accident.


In-Flight Failure of a Composite Rotor Blade

An emergency medical helicopter was dispatched to an accident scene alongside an unpopulated stretch of roadway. The helicopter crew navigated by GPS and adjacent to the accident scene the helicopter struck power lines and crashed. The wreckage scatter diagram showed the blades all were thrown in the same direction and within close proximity to each other, versus each scattering outwards in a different direction. DVI’s Helicopter Maintenance and Composites Experts were retained to defend the rotor blade overhaul shop and investigate the cause of the rotor blade separation. DVI’s Aviation Experts performed extensive testing to replicate and analyze the maintenance shops procedure for replacing the leading edge abrasion strip, which was allegedly responsible for the composite rotor blade failure. All exemplar and subject testing, physical evidence, and wreckage scatter did in fact indicate that the composite blades struck the power lines, and that truly was indeed the actual cause of the accident.


Crash-worthiness of Composite Airframe Structures

A pilot brought his aircraft in for a normal and routine oil change. Unfortunately, the maintenance shop neglected to safety wire the oil drain plug. Shortly after departure, the oil drain plug loosens, resulting in a sudden engine seizure. The pilot elected to make an off field emergency landing in a corn field. Due the height of the corn, and the selection of partial flaps, the aircraft stalls slightly above the soft mud, and decelerates quickly. While plowing into the soft mud, the engine structure separated from the structure and entered the cabin structure from underneath the forward cabin structure. DVI’s Composite and Reconstruction Experts were hired to evaluate the forces the occupants experienced, and determine if those forces were survivable. DVI’s Aviation Experts reconstructed the speeds and loads associated with the flight and plowing on the ground, the force of the impact with the engine structure, and measured the airframe, seat, and landing gear deformation.


Determining the Cause of a Jammed Flight Control Surface

During a routine training flight a student pilot and a certified flight instructor were practicing spins and spin recovery. Witnesses on the ground saw the aircraft spinning and impact the ground in a nose low attitude. In the wreckage, the rudder control horn was found to be caught on the rudder stop bolt. DVI’s Aircraft Reconstruction Experts were hired to determine if the rudder became jammed in flight or was a consequence of the impact with the ground. DVI’s Aviation Experts fabricated a test rig using and an actual aircraft fuselage, and performed extensive laboratory testing to determine what combination of factors and forces would be necessary for the rudder to snag on the stop bolt.


Recreating an Accident Flight Path for Demonstrative Evidence

A pilot purchases an aircraft with a high time engine. On the flight back to his home airport, the pilot has a complete engine failure. The pilot is over terrain that is covered by approximately 50% woods intermingled with unplowed farm fields. The pilot attempts to stretch his glide to a landing site, and crashes into a heavily wooded area. DVI’s Aircraft Reconstruction Experts were hired to recreate the flight path, and identify all available landing sites that would have been available to the pilot at the time of the engine failure, given his altitude and airspeed. The multi-media demonstrative evidence allowed DVI’s clients to explain to the jury what the pilot’s options were at the time of engine failure. The multi-media demonstrative evidence included actual in-flight footage, overlaid on top of satellite imagery, with glide path calculations to each alternate site.


In-Flight Separation of a Wing

A pilot had volunteered to fly a medical transportation flight in his twin engine aircraft. At, 10,000 feet, the last recollection of the pilot was seeing the sun set in the distance, and then seeing the VSI pegged downwards. One of the passengers recalls feeling three “bumps” and then an extreme pressure on her belt, and then a sudden release. Radar data and wreckage diagrams showed the aircraft came apart at around 10,000 feet, and miraculously the pilot and one of the passengers survived the fall, their impact cushioned by the forest below. DVI’s Accident Reconstruction and Aircraft Maintenance Experts were retained by the maintenance shop that performed the last annual, to determine the cause of the in-flight breakup. DVI’s Aviation Experts were able to identify the correct sequence of the in-flight separation, and during the subject inspection discovered circumferential cracks in the Janitrol heater. The Janitrol heater was never inspected or even disassembled by the NTSB. The cause of the accident was determined to most likely be carbon monoxide poisoning and temporary incapacitation of the pilot.


Measuring the Force of a Runaway Trim Motor In-Flight

An elderly pilot is flying some friends on trip up the coast of California. Radar data indicated that the plane climbed slightly before spirally into the ocean. DVI’s Aircraft Accident Reconstruction Experts were retained by the maintenance shop that performed maintenance on the aircraft trim and autopilot system. DVI’s Aviation Experts developed a flight test protocol and instrumented an exemplar aircraft with load cells, to measure the actual control forces that a runway trim motor would cause. DVI performed comprehensive flight testing in all possible configurations and airspeeds, while measuring the force to counteract opposing trim forces. DVI’s testing was instrumental in bringing about a mediation.  

Failure of a Landing Gear to Extend

A twin-engine turbine aircraft was inbound for a landing, and the plot was unable to extend the main landing gear. DVI’s Aircraft Maintenance Expert was sent the actuator for a non- destructive testing, and to facilitate a multi-party inspection. DVI's Aviation Experts first took the part and had x-rays taken to document the subject evidence prior to disassembly. Fractured components were discovered in the actuator, and the fracture surfaces were examined under high power microscopes. DVI was able to research and trace the source of manufacture of the broken component, and found it was an approved part, and that the OEM part had not been available for over 15 years.

Ground Tug Striking a Terminal Building

A large aircraft tug pushes a 737 back from the terminal. After releasing the aircraft the operator attempts to return to his parking spot in front of the terminal, but has a complete brake failure and impacts the building. The impact with the building is sever enough that the tow tug penetrates the wall, and enters the passenger waiting area. DVI's Ground Vehicle Experts were retained to investigate the accident and determine the cause of the brake failure. DVI's Aviation Experts inspected the subject tug, and performed a series of brake tests with data acquisition sensors. DVI's experts were able to quantify the amount of degraded braking capabilities and identify the cause of the loss of braking power.


In-Flight Bird Strikes

A medium size bird impacts a helicopter flying at a low altitude. The impact ultimately causes the helicopter crash. For our client, DVI's Helicopter Experts researched and created a comprehensive matrix of windshield designs and control locations for helicopters manufactured worldwide. This was a one of a kind matrix, and assisted the client in evaluating the appropriateness of the design configuration of the accident helicopter.