Prior to descent into Coolangatta, the crew of the Boeing 717 aircraft noticed a low right hydraulic quantity warning. After following the abnormal checklist and turning off the right hydraulic system, the pilot in command decided that, due to the rudder reverting to manual mode and the loss of operation of two ground spoilers, he would divert the aircraft to Brisbane where a longer runway was available. After advising Brisbane Air Traffic Control of the hydraulic failure, and that a faster than normal landing would be carried out, the airport's emergency services were placed on standby.
With the right hydraulic system turned to the OFF position, the aircraft's landing gear had to be manually lowered using the emergency gear extension lever. That operation did not close the main landing gear doors after the landing gear was extended. In accordance with the abnormal check list an attempt to close the doors was conducted by the crew after receiving the green down and locked indication for the landing gear. However, following the selection of the right hydraulic system to ON, a rapid drop in hydraulic fluid quantity was noticed so the OFF position was immediately re-selected before the doors had closed.
As the aircraft touched down, the main landing gear doors contacted the runway surface. Although the doors were fitted with non-sparking polyurethane rest bumpers, the runway centerline lights were contacted creating sparks that were observed by ground personnel. The aircraft was then brought to a halt on the high speed taxiway where an engineer was requested to manually close the main landing gear doors. Following closure of the doors the aircraft taxied to the terminal. The abnormal checklist stated that the aircraft is not to be taxied but may be towed after landing gear safety pins had been fitted and main landing gear doors closed.
An inspection of the aircraft by the operator revealed that a hydraulic pipe from the right engine driven hydraulic pump had failed at its brazed fitting, resulting in the loss of hydraulic fluid from the right hydraulic system. As this was not the first time that the operator had experienced such a failure of hydraulic pipes, the aircraft manufacturer was contacted. It was determined that the pipes in the area of the rear fuselage were being subjected to vibration from the engine driven hydraulic pump, which in some cases resulted in the fracturing of the pipe fittings.
Local safety action
As a result of the investigation, the following safety actions were carried out:
The operator issued a memo to its engineering staff highlighting the need for:
- extra vigilance when inspecting the rear fuselage area; and
- all hydraulic fluid leaks to be treated as potential total hydraulic failure and to be reported to maintenance watch.
The engine buildup unit contractor issued Service Bulletin, Rohr SB R715.29-001 on 9 November 2001, that provided instructions to install a pulsation attenuator to each engine driven hydraulic pump.
The airframe manufacturer issued an All Operators Letter (AOL) 717-048 on the 18 January 2002, recommending that operators install the hydraulic pump outlet attenuator (via Rohr Service Bulletin R715.29-001) to minimize hydraulic system vibrations.
|Date:||18 October 2001||Investigation status:||Completed|
|Time:||2130 hours EST|
|Release date:||01 May 2002||Occurrence class:||Technical|
|Report status:||Final||Occurrence category:||Incident|
|Highest injury level:||None|
|Aircraft manufacturer||The Boeing Company|
|Type of operation||Air Transport High Capacity|
|Damage to aircraft||Minor|
|Departure point||Sydney, NSW|
|Departure time||2030 hours EST|
|Role||Class of licence||Hours on type||Hours total|