Network Australia F100 at Perth on Sep 23rd 2016, hydraulic problem, fumes on board

Last Update: February 9, 2017 / 15:08:14 GMT/Zulu time

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Incident Facts

Date of incident
Sep 23, 2016

Classification
Incident

Flight number
QF-1623

Destination
Perth, Australia

Aircraft Registration
VH-NHY

Aircraft Type
Fokker 100

ICAO Type Designator
F100

A Network Aviation Australia Fokker 100 on behalf of Qantas, registration VH-NHY performing flight QF-1623 from Newman,WA to Perth,WA (Australia) with 97 passengers and 5 crew, was on approach to Perth, when the crew reported hydraulic problems advising they would possibly not be able to vacate the runway, emergency services deployed to their stand by positions. The aircraft continued for a safe landing on Perth's runway 21 and rolled to the end of the runway. During roll out fumes began to develop in cabin and cockpit prompting the crew to stop the aircraft after vacating the runway and initiate an evacuation of the aircraft via slides onto the taxiway. Three passengers received minor injuries as result of the evacuation.

Passengers reported they were unaware of any issue prior to the fumes developing as the aircraft rolled out. The fumes were consistent with the odour of some sort of oil.

The airline reported there was no emergency landing, however, emergency services were called on stand by for the landing by the crew as a precaution. As the aircraft began taxiing towards the terminal, flight attendants alerted the captain of fumes on board, the captain decided to evacuate the aircraft.

Australia's TSB reported the crew received a hydraulic warning during the approach, after landing fumes were detected in the cockpit and the crew initiated an emergency evacuation. The occurrence was rated an incident, an investigation has been opened.

On Feb 9th 2017 the ATSB released their final report concluding the probable causes of the incident were:

- A damaged O-ring in the left engine thrust reverser selector valve resulted in a hydraulic leak.

- Hydraulic fluid, or vapour, entered the APU air intake through a gap between the APU intake door actuator rod cut-outs.

- The cabin fumes were the result of the APU supplying air contaminated with hydraulic fluid to the air-conditioning system after the ground-flight logic switch detected the aircraft on the ground, which resulted in the contamination of the air-conditioning system.

- The R1 door slide did not deploy automatically because the door was disarmed when it was opened.

The ATSB reported the #1 hydraulic system showed low quantity. The crew worked the related checklists and shut the #1 hydraulic pumps down. The loss of the system meant, alternate gear extension was needed, the flaps would be electrically extended and the nosewheel steering, speed brakes and thrust reversers were inoperative. The crew therefore planned to land on Perth's runway 21, roll to the end of the runway where a tug should wait for them and tow them off the runway to the apron. The captain decided to start the APU so that while on tow they wouldn't need the engines for electrical power and air conditioning during the tow. The crew declared PAN and advised ATC of their intentions.

The aircraft landed on runway 21, the crew could see the tug waiting for them at the end of the runway, the crew used differential braking to steer the aircraft off the runway onto the taxiway and stopped. After landing checks the captain talked to the cabin crew and was informed of fumes. The captain turned the APU bleed air off, cabin crew reported the fumes got even worse, the crew therefore suspected the fumes originated from the engines and initiated an emergency evacuation. The forward left door (L1) slide did not automatically inflate, the flight attendant inflated the slide manually. The right hand forward slide (R1) did not inflate, the flight attendant blocked the door, the evacuation thus was done through door L1 and the overwing exits. Cabin crew needed to direct a number of passengers to leave their luggage behind. Three passengers received minor injuries in the evacuation.

Maintenance found the #1 engine thrust reverser selector valve, located in the left outboard APU compartment, leaked hydraulic fluid contaminating the APU and air conditioning system via the APU inlet. The ATSB wrote: "A gap between the APU intake door actuator rod cut-outs was identified as the path for contaminated air to enter the APU inlet. When the APU inlet door is open inflight, air is scooped into the inlet creating an area of high pressure. However, when the aircraft is on the ground with the APU running, the APU inlet becomes an area of lower pressure as the APU is now ‘sucking’ air into the inlet." The ATSB further explained: "If the APU is started while airborne, it will not supply air to the air-conditioning system until the ground-flight logic switch detects the aircraft is on the ground."

Maintenance found the door R1 selected to "DISARM".

The ATSB analysed:

The hydraulic leak was the result of a failure of an O-ring in the number 1 thrust reverser selector valve. The checklist actions resulted in switching off the pumps supplying the number 1 hydraulic system with the loss of the associated systems, which included the nose wheel steering. The loss of nose wheel steering necessitated a tow to the gate by a tug after landing. The captain elected to start the APU inflight so that it would be available to supply air for the air-conditioning system after landing and electrical power after the engines were shutdown. However, unknown to the flight crew, the location of the hydraulic leak relative to the APU air intake, and a gap between the APU intake door actuator rod cut-outs, resulted in the contamination of the air-conditioning system. This occurred when the ground-flight logic switch detected the aircraft was on the ground and the APU started to act as a source of air supply for the air-conditioning system.

After the fumes were detected in the cabin, the first action by the captain was to switch off the air supply from the APU. Following this action, the air for the air-conditioning system was supplied by the engines. However, by this stage various parts of the air-conditioning system were contaminated with hydraulic fluid. Therefore, fumes continued to enter the cabin through the air-conditioning system.

During the emergency evacuation, the R1 door slide did not deploy. The maintenance inspection found the R1 door was disarmed and no fault was found with the door operating mechanism. Therefore, it is likely that during the emergency evacuation procedure the cabin crewmember at the R1 door reverted to previous experience and disarmed the door prior to opening it, which prevented the slide from automatically deploying.
Incident Facts

Date of incident
Sep 23, 2016

Classification
Incident

Flight number
QF-1623

Destination
Perth, Australia

Aircraft Registration
VH-NHY

Aircraft Type
Fokker 100

ICAO Type Designator
F100

This article is published under license from Avherald.com. © of text by Avherald.com.
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