2nd of September 2008, Blog #525
With 40 passengers onboard an Embraer RJ 190-100 LR was operating a scheduled passenger flight from Brisbane (Queensland, Australia) to Honiara (Solomon Islands). The take-off and the initial claim were uneventful. Two pilots and three cabin staff crewed the flight.
Fuel venting in flight as seen from the cabin (Source; ATSB © Cabin crew on the incident flight)
At approximately 08.45 lt (local time), while climbing through flight level (FL) 250 the aircraft encountered moderate turbulence. (Aircraft flight data revealed that the turbulence recorded accelerations varying from 0.6 to 1.4 G. Airspeed at the time varied from 270 KIAS to 290 KIAS. During the turbulence encounter, the vertical speed ranged from -1232 ft/min to 4880 ft/min. During the turbulence encounter, the cabin crew alerted the flight crew that "vapour" was seen streaming from both wings. The captain went back to the cabin to check and confirmed the observation by the cabin crew. Fuel was venting from both wing tanks. The necessary checklists were completed and ATC was informed about the issue, and a return to Brisbane was requested. When the return was approved by ATC the aircraft ha reached FL 370, while fuel was still leaking from the wing. During the descent, ~eight minutes after the start of the descent, the fuel leak stopped. When the aircraft was configured for landing at Brisbane, at an altitude of ~4000 feet the fuel leak resumed.
Flight Data from the incident (© ATSB)
The landing at Brisbane was uneventful and the aircraft was stopped clear of the runway and inspected by the airport rescue and fire fighting crews, no leakage was reported.
The Australian Transport Safety Bureau (NTSB) was alerted of the incident and an investigation was launched. The operator downloaded the aircraft flight data and provided this data to the NTSB. The operator also provided fuel data from the flight to the investigators. The departure fuel of the aircraft had been 12.800 kg (6400 kg) per wing. after landing the indicated fuel quantity was 9600 kg. 2600 kg were used by the engines during the flight. this meant that 600 kg of fuel had been lost due to the leak. During the investigation, it became clear that under certain flight conditions (climbing from FL220 to FL320, with a speed above 300 KIAS) a fuel leakage from the left wing NACA inlet underneath the wing. The aircraft manufacturer had issued an Operation Bulletin number 170-001/07 titled, titled "FUEL LEAKAGE THROUGH NACA INLETS" describing this phenomenon. However, this bulletin was not made available to the operator by the aircraft manufacturer.
When the ATSB concluded their investigation it published the following findings in its report;
Under certain flight conditions, if the aircraft is equipped with a part number 2930015-102 float vent valve, the Embraer RJ 190-100 aircraft fuel system is susceptible to fuel venting/leakage through the wing NACA inlets. [Safety issue]
The aircraft manufacturer did not make Operation Bulletin number 170-001/07 available to the operator on their electronic online document access system. [Safety issue]
During climb out while passing through FL250 at 290 KIAS, the aircraft encountered turbulence and large variations in vertical speed, which probably permitted positive pressure in the main wing fuel surge tanks to decrease, allowing fuel to leak from the NACA inlets.
The aircraft computed airspeed values momentarily exceeded the climb schedule and airspeed recommended by the aircraft manufacturer’s Operation Bulletin number 170-001/07.
Several safety actions were taken by the aircraft manufacturer after the publication of the investigation report. The investigation report, on which this blog is based, is available for the readers' reference by clicking on the .pdf file below.