Created Saturday, Oct 24th 2020 20:16Z, last updated Monday, Aug 29th 2022 16:12Z
An Envoy Embraer ERJ-145, registration N674RJ performing flight AA-4194/MQ-4194 from Miami,FL (USA) to Freeport (Bahamas) with 25 passengers and 3 crew, landed on Freeport's runway 06 at 11:56L (15:56Z) but veered right off the runway and came to a stop on soft ground with both main gear struts collapsed after complering a near 180 degrees turn heading against landing direction. Two passengers received minor injuries.
Bahamas' AAIA have opened an investigation. Preliminary information suggests a landing gear malfunction caused the runway excursion.
The airline reported later that the aircraft had experienced an issue with the main landing gear.
On Jun 11th 2021 the AAIA released their preliminary report stating:
According to the crew’s statement post-accident, the flight was uneventful up until the point just after landing. The crew reported that the approach was stable, contact was made with the runway and immediately after touchdown they both experienced a sudden braking of the aircraft, although no control inputs were being made. Subsequently, there was a rapid deceleration of the aircraft followed by a skidding action. The pilot in command (who was the pilot flying on this leg of the flight) was unsuccessful in his attempts to stabilize and control the aircraft as it continued down the runway, eventually veering off the centerline, and coming to a stop off the right runway shoulder. During the excursion sequence both main gears collapsed. The tail section of the aircraft was the most exposed to the active runway as it came to rest approximately 15 ft. from the runway’s edge.
Bahamas' AAIA released their final report concluding the probable causes of the accident were:
Based on evidence gathered, CVR and FDR data analysis and analysis conducted of suspected components, the probable cause of the heavy braking action that resulted in the runway excursion could not be replicated or determined.
Results of functional tests of components suspected of contributing to the heavy braking action that occurred are as follows:
- Brake control unit (BCU), PASS
- Emergency parking brake pressure switch PASS
- Emergency parking brake handle and cable PASS
- Parking brake valve – all tests passed except for internal leakage in the “Off” position – 4 drops in 5 min (requirement: not to exceed 1 drop in 5 min). The component manufacturer and Embraer stated that this issue would have no effect on braking performance but could result in excessive hydraulic pump operations in order to maintain system pressure. Additionally, slight deviations were noted on operational test but this was determined to have minimal effect on brake pressure application.
Cause of Accident – Undetermined
The AAIA analysed:
There were no indications on the aircraft flight data recorder or cockpit voice recorder of an abnormal or emergency situation related to an aircraft system malfunction prior to landing.
BRAKING ACTION
According to statements by the flight crew, immediately after touchdown, there was a sudden and unexpected braking of the aircraft. On site investigation, as well as post-accident investigation, documented heavy braking action from tires of both main landing gear on the runway from the point of touchdown to the point of the runway excursion.
Heavy braking signature marks are indicative of possible brakes being engaged at the point of landing and throughout rollout, up to the point of runway excursion.
As a result of evidence of heavy brake signature markings, additional analysis were conducted of several components related to the braking system of the aircraft, which were suspected of being contributory to the accident.
COMPONENT EXAMINATIONS
The brake control unit (BCU), parking brake valve, emergency parking brake handle and cable, and the emergency parking brake pressure switch were all removed, quarantined, and then shipped to their respective manufacturers for testing and analysis.
BRAKE CONTROL UNIT
As an integral component of the EMB-145’s brake system, the Brake Control Unit (BCU) is responsible for controlling and monitoring the normal brake system of the aircraft and facilitates sending appropriate signals to the crew alerting system and other systems in the event of a malfunction.
The component examination conducted was to identify, via analysis of non-volatile memory (NVM) data and testing, any system defects or anomalies that may have contributed to the accident sequence of events.
The testing conducted found no faults and there were no irregularities with the data analyzed. This result is consistent with the flight crew’s statement as well as the CVR and FDR analysis in that there were no aural or visual indications, via the crew alerting system, of any braking system failure or malfunction.
EMERGENCY PARKING BRAKE HANDLE AND CABLE
The emergency parking brake handle and cable serves as the mechanism that actuates the emergency parking brake valve via hydraulic pressure. To set the parking brake, the handle is pulled and rotated to the fully-actuated position.
Testing of both the handle and cable was conducted to assess the operability of the components and additionally, the extent to which a partial or total actuation could have taken place independently during
taxi or takeoff phases.
A thorough visual inspection and testing of the components indicated that the parts were functional and presented no difficulty in use. As such, the component was ruled out as contributory to the occurrence of the accident.
EMERGENCY PARKING BRAKE VALVE
A series of tests were conducted to determine the functionality of the component and the presence of any evidence indicating a failure or malfunction of the part.
The only test to not pass was the internal leakage test which produced four (4) drops in five minutes but was not to exceed one (1) drop in five minutes. It was determined that this result was of no consequence in relation to the aircraft’s braking performance.
EMERGENCY PARKING BRAKE PRESSURE SWITCH
During bench testing of the emergency brake pressure switch, there were no abnormalities or irregularities found and testing was completed satisfactorily.
During normal system operation, once emergency parking brake is engaged, there are two visual warning indication lights, one on the main panel and the other on the ramp panel.
