Brazil

It is possible that the pilot applied the flight controls inappropriately when the aircraft returned to the runway, making it impossible to maintain direction. After the 'door warning' light activated, the pilot made the decision to land when, according to the manufacturer, the situation did not require such immediate action but a continuation of the climb. It is possible that the pilot's training was not adequate or sufficient, because after the 'door warning' light came ON and the abnormal vibrations, the pilot carried out a procedure different from the one recommended by the manufacturer, and placed the plane in an irreversible condition.

The following findings were identified:
- The LEFT MAIN LANDING GEAR ASSEMBLY (PN D23189000-19 and SN MN1700) collapsed, failing with 5,130 cycles after the last overhaul.
- A specific component (pin) of the assembly connecting the landing gear to the airframe, the AFT PIVOT PIN (P / N D61000, S / N 25), broke on account of fatigue, whose onset was facilitated by a machining process carried out in the pin section transition region.
- The ANAC-approved ATR72 Series Aircraft Maintenance Program of the TRIP Linhas Aéreas company read that the LEFT MAIN LANDING GEAR ASSEMBLY had to undergo overhaul every eight years or 18,000 cycles.
- On 27 February 2009, the PR-TTI landing gear was removed and, on 09 March 2009, was sent to be overhauled by the AV Indústria Aeronáutica Ltda. It had 31,684 cycles since new and 18,095 cycles since the last overhaul.
- AV Indústria Aeronáutica Ltda. was homologated for conducting such inspection, as specified in the List attached to the Addendum, Revision no. 11, dated 05 January 2009, and accepted by means of the Official Document no. 0173/2009-GGAC/SAR, issued by the Civil Aviation Authority.
- The AV Indústria Aeronáutica Ltda. company disassembled the legs of the landing gear, and outsourced some of the tasks for not possessing technical knowledge and/or appropriate machinery (necessary for the process of reconditioning the AFT PIVOT PIN (D61000 SN 25).
- Two of the three companies outsourced by AV Indústria Aeronáutica Ltda. were not homologated by the Civil Aviation Authority.
- The AV Indústria Aeronáutica Ltda. company conducted external audits of the three companies involved in the overhaul.
- The audits carried out by AV Indústria Aeronáutica Ltda. were not sufficient to identify that the contractors lacked qualified personnel, manuals and the machinery necessary to work with aeronautical products.
- The AV Indústria Aeronáutica Ltda. Technical Manager did not supervise the overhaul inspections and services performed by the contracted companies.
- The AFT PIVOT PIN (D61000 SN 25) is part of the assembly that connects the landing gear to the airframe.
- All revision tasks were described in the manuals of the manufacturer.
- The AFT PIVOT PIN (D61000 SN 25) failure-analysis report stated that the PRTTI aircraft left main landing gear collapsed on account of fatigue, whose onset was facilitated by a machining process carried out in the section transition region of the pin.
- The manufacturer's maintenance manual did not refer to any machining work in that region of the pin.
- In only one stage of the pin reconditioning process was it possible to observe that a machining task was required, namely, the Grinding of chromium.
- The lack of capacitation and training of the subcontractors’ professionals for handling aircraft material hindered the execution of an efficient maintenance work as prescribed by the manufacturer's manual, culminating in inadequate machining during the maintenance process.
- The lack of an effective process of supervision, both on the part of TRIP Linhas Aéreas and on the part of the other contractors and subcontractors allowed the existing maintenance services’ latent failures not to be checked and corrected, in a way capable of subsidizing, in an adequate and safe manner, the execution of the landing gear maintenance service.
- The process of supervision of the TRIP Linhas Aéreas and the AV Indústria Aeronáutica Ltda. companies by the Civil Aviation Authority, prescribed by specific legislation in force, was not enough to mitigate the latent conditions present in the accident in question.
- According to the technical opinion issued by the DCTA, the AFT PIVOT PIN (D61000 and SN 25) presented fracture surfaces with ± 45º inclination, as well as a flat area with multiple initiations, indicative of a fracture mechanism related to fatigue. In examinations of the external surface of the pin, in a region close to the fatigue fracture, cracks were observed that had initiated from scratches created by an inadequate maintenance machining process. In the region where the overload-related fracture occurred, it was also possible to identify that the machining process had modified the profile of the part in the section transition region, by producing a depression. Thus, it can be said that the AFT PIVOT PIN (D61000 and SN 25) of the PR-TTI left main gear broke on account of fatigue, whose onset was facilitated by an inadequate machining process that had been performed in the section transition region of the pin.

The following findings were identified:
- Factors, such as obesity and sedentariness, associated with the high workload in the moments preceding the collision with the hill, may have contributed for the task demand to exceed the margins of safety, resulting in wrong decision-making by the pilot.
- Upon facing adverse meteorological conditions and being aware that aircraft which landed before him had reached better visibility in altitudes below 3,500 ft. on the final approach of the VOR procedure, the pilot may have increased his level of confidence in the situation, to the point of descending even further, without considering the risks involved.
- The weather conditions encountered in the final phase of the flight may have aggravated the level of tension in the aircraft cabin to the point of compromising the management of the situation by the pilot, who delegated responsibility for radiotelephony communication to a passenger.
- If one considers that the pilot may have decided to descend below the minimum safe altitude in order to achieve visual conditions, one may suppose that his decision, probably influenced by the experience of the preceding aircraft, was made without adequate evaluation of the risks involved, and without considering the option of flying IFR, in face of the local meteorological conditions. In addition, the pilot’s decision-making process may have been compromised by lack of information on Mount Santo Antonio in the approach chart.
- The primary radar images obtained by Anápolis Control (APP-AN) indicated the presence of thick nebulosity associated with heavy cloud build-ups on the final approach of the VOR procedure. Such meteorological conditions influenced the occurrence, which culminated in the collision of the aircraft with Mount Santo Antônio, independently of the hypotheses raised during the investigation.
- The final approach on the course 320º, instead of 325º, made the aircraft align with the hill with which it collided.
- Mount Santo Antonio, a control obstacle on the final approach in which the collision occurred, was not depicted in the runway 32 VOR procedure approach chart, in discordance with the prescriptions of the CIRTRAF 100-30, a fact that may have contributed to a possible decrease of the situational awareness.

The following factors were identified:
- During the approach, the flight crew's attention was focused on the characteristics of the geographical relief and presence of birds, reducing their awareness as to the maintenance of the approach slope.
- The group culture of maintaining a low angle of approach led the crew to choose the runway aspect instead of the VASIS as a reference for the approach, making them susceptible to various types of spatial illusion.
- Taking into account copilot's report that he was not succeeding in correcting the aircraft glide path relative to the runway, one may suppose that he was not applying the appropriate amplitude for such correction.
- The physical characteristics of the runway 15 (the active one) contributed to a wrong perception of the ideal glide path. The pronounced acclivity of the runway, its width (narrower than the runways on which the crew was accustomed to operate), and the low terrain near the threshold, caused in the pilots a perception that they were above the ideal approach slope, leading them to seek correction, which resulted in an angle of approach below the ideal one.
- For the flight in question, the company chose two pilots who had never operated in SBQV. A crewmember with previous experience in the locality would have a higher level of awareness in relation to the specific characteristics of the aerodrome.
- No company publications were found that could provide the pilots with guidance on the specifics of SBQV, capable of helping with the management of the risks associated with the operation in that aerodrome.

An error in the assembly was detected in the left generator, which interfered with the D+ terminal signal sent to the voltage regulator. Due to a voltage drop, some of the instruments lost their functionality. The following contributing factors were identified:
- The crew did not follow the emergency procedures;
- The crew decided to return to land at Santos Dumont Airport without considering that the runway length was less than the length required for an emergency landing;
- The speed of the aircraft while passing over the runway threshold was 25 knots above the reference speed;
- The pilots were unable to engage the spoilers or the thrust reversers;
- Wrong attitude from the captain;
- Overconfidence of the crew;
- Emotional load due to an emergency situation;
- Poor assessment of the situation due to high stress associated with decreased situational awareness;
- Poor crew coordination;
- Lack of crew resource management;
- Poor judgment;
- Lack of procedures on the part of the operator.

Controlled flight into terrain after the crew descended too low in IMC conditions. The following contributing factors were identified:
- Visibility was below minimums,
- The crew continued the descent until the aircraft impacted ground and failed to initiate a go-around procedure,
- A probable crew fatigue,
- It is possible that the crew suffered optical illusions,
- Overconfidence on part of the captain,
- The captain did not request any assistance from the copilot during the approach procedure,
- Inexperienced, the copilot did not interfere despite dangerous flight conditions,
- Poor organizational culture,
- Deficiencies in crew training,
- Lack of crew discipline,
- Poor flight planning,
- Lack of supervision on part of the operator,
- The copilot was inexperienced on this type of aircraft.

The following findings were identified:
- The external tyre on the right main gear deflated during the takeoff roll,
- The crew retarded the power levers and deployed the spoilers,
- The crew did not use the parachute, judging the relative low speed and thinking this was an optional equipment,
- Technical analysis on the right main gear revealed that the six bolts on the external wheel torque were approximately 90% lower than foreseen, which may contributed to the tyre deflection.

The following findings were identified:
- Weather conditions made it difficult for the crew to locate the runway;
- The crew failed to follow the emergency procedures and was unable to keep the aircraft level;
- The captain did not feather the left propeller, which resulted in increased drag and reduced aircraft speed;
- The engine maintenance did not meet the engine manufacturer's requirements;
- No technical overhaul of the left engine had been carried out despite the fact that the 12-year calendar limit set by the manufacturer had been exceeded;
- A nipple mounted on the left propeller governor was not intended for aeronautical use;
- The poor seal caused by the improper connection allowed the pressure to drop, resulting in a loss of power on the left engine;
- Poor organizational culture by the operator, which compromised the safety of the operation;
- The company did not have an effective supervision program;
- Poor judgment on part of the captain;
- Poor aircraft maintenance.