CEN11FA193

The pilot flying's (PF) decision to land on a shorter-than-recommended runway with a known left hydraulic system failure rather than go around as suggested by the pilot-not-flying, his failure to immediately apply emergency brakes following the detection of the lack of normal brakes, and his attempt to go around late in the landing roll with insufficient runway remaining. Contributing to the accident was the nose landing gear swivel assembly failure, the lack of a hydraulic fuse before this critical failure point, and the design of the swivel using two similar alloys with a propensity to adhere to each other when rubbed together. Also contributing to the accident was the lack of a disciplined cockpit environment.

While the airplane was inside the final approach fix, an amber left side hydraulic quantity low crew alerting system (CAS) message illuminated. The pilot flying (PF) noticed the hydraulic fluid quantity decreasing. Subsequently, an amber left hydraulic system fail CAS message appeared. The pilot not flying (PNF) pulled out the checklist to accomplish the left hydraulic system failure procedures and then suggested a go-around because the landing runway was about 500 feet shorter than the recommended minimum runway length indicated in the checklist. The PF decided to land due to the hydraulic quantity indications, prior autopilot problems, and the airplane's landing configuration. The PNF turned on the auxiliary pump about 500 feet above ground level, and both the PF and PNF thought the auxiliary hydraulic system could support normal spoilers, brakes, and nosewheel steering. The PF selected right thrust reverser aft and began pressing the brakes, but he felt no braking action. He reached for the emergency brakes; however, he did not immediately apply them to slow the airplane because he decided that there was not enough distance remaining to stop the airplane on the runway. Therefore, he attempted to go around with insufficient runway remaining by advancing the throttles to the maximum continuous thrust setting. The PNF did not see the airspeed increase and believed that not enough runway remained to get airborne, so he pulled the throttles back to avoid a runway overrun. The airplane exited the runway and sustained substantial damage. A review of the cockpit voice recorder transcript indicated that, before the emergency, the flight crew did not maintain a disciplined cockpit environment that focused on operationally relevant discussion but instead repeatedly made reference to and discussed objects on the ground and other operationally irrelevant topics. The lack of a sterile cockpit did not promote crew coordination and communication and adherence to procedures, which would have helped mitigate this emergency. A postaccident examination of the airplane revealed that the nose landing gear swivel assembly, which had passed an acceptance test procedure before its installation on the airplane, was seized and bound and had a fracture on its inboard connecting tube, which was the site of the hydraulic fluid leak. The swivel assembly had galling wear scars on the outside diameter of the spool and the inside diameter of the housing; both the spool and housing were made from similar aluminum alloys that have a propensity to gall and adhere to each other when rubbed together. The connecting tube fracture was consistent with a single bending and torsional overload event associated with high opening forces or seizure in the center swivel due to galling wear. The center housing/spool seizure was consistent with a misalignment of the swivel, which led to the binding together of the similar aluminum alloys of the spool and housing. Further examination showed that the nose landing gear hydraulic system did not have a volumetric hydraulic fuse designed to minimize the loss of hydraulic fluid in the event of a line break downstream of such a device.

The parameters evaluated for the purpose of this report appeared to be in accordance with the federal FDR carriage requirements, except Relative Time and Pressure Altitude. There appears to be a discrepancy between the sampling rate requirements in 14 CFR Part 91 and the sampling requirements for 14 CFR Part 135 and 14 CFR Part 121. The accident aircraft recorded Relative Time once every 4 seconds and Pressure Altitude once every second, which meet the requirements for 14 CFR Part 135 and 14 CFR Part 121; whereas Appendix E to 14 CFR Part 91 specifies the sampling interval for Relative Time to be once per second and Pressure Altitude to be 11 per second. Gulfstream's submission, in part, stated: Gulfstream believes that the published 14 CFR Part 91 Appendix E is typographically incorrect as it does not harmonize with the [Minimum Operational Performance Specification For Crash Protected Airborne Recorder Systems ED-112] and Parts 121 and 135. The sampling requirement for "Time or Relative Time" should be once every 4 seconds for Parts 91, 121 and 135. The sampling requirement for "Pressure Altitude" should be once every second for Parts 91, 121 and 135. Gulfstream representatives, along with representative from GAMA (General Aviation Manufacturers Association) discussed this with an FAA Recorder Specialist during the June 14, 2012 US/Europe International Safety Conference. The FAA representative stated that this issue has been known for at least 12 months and it is indeed a typographical error that will be corrected on the next revision to 14 CFR Part 91 appendix E. FDR data frame correlation documentation is required in 14 CFR Part 121.343(j), 14 CFR Part 121.343a(d) and 14 CFR Part 135.152(f)(2). In contrast, FDR data frame correlation documentation is not required for 14 CFR Part 91.609. However, FDR data frame documentation is essential for decoding FDR data. Upon request, Gulfstream provided the FDR documentation to the NTSB but the documentation was insufficient to decode the data and difficult to understand. Therefore, it was necessary to have Gulfstream's assistance in decoding and verifying the data. Gulfstream's reference to FDR Documentation in their submission, in part, stated: Subsequent to the FDR Group Meeting, Gulfstream revised GVSP-GER-6098 revision j (rev j) … and provided a copy to the NTSB. The NTSB has since commented on GVSP-GER-6098 (rev j), noting "editorial errors and inconsistencies". Gulfstream has made improvements to GVSP-GER-6098 (rev k) to address the editorial errors and inconsistencies. … While rev k is improved, Gulfstream recognizes that this document will need a thorough reexamination and modification. Gulfstream has accepted this as a follow-on task and will execute appropriately. Gulfstream's reference to Quick Reference Handbook (QRH) procedures in their submission, in part, stated: The [QRH] procedure checklist for Left Hydraulic System Failure at the time of the accident had two separate procedures, one dealing with loss of Left system pressure and fluid, and the other dealing with loss of Left and Aux Hydraulic system. Both of those procedures had the identical caution with the statement: "To verify the availability of Auxiliary system fluid, select the Aux pump on for a minimum of 30 seconds and check for Auxiliary system pressure. If pressure cannot be maintained, assume that the Auxiliary system is not available and proceed to the Left System and Auxiliary Hydraulics System Loss of Fluid." The reason for the caution on both checklists is that the synoptic indication of fluid in the Aux system is predicated on the piston position for fluid in the Left system reservoir and not the actual fluid in the Aux system. The only quantity enumerated is for the fluid in the Left system and not the Aux. If the Left system reservoir piston is positioned to empty, the Aux system will indicate empty, even if fluid is present. The only reliable check of fluid being present in the Aux system is the ability to maintain system pressure. That is why it is imperative for the crew to note the caution and complete the directed action. The change to the QRH in the case of experiencing a Left Hydraulic System failure now incorporates the assumption that upon the failure of the Left Hydraulic System, the Aux system is lost as well. The procedure plans for the worst case scenario of losing all Left and Aux fluid upon touchdown, directing the crew to prepare for landing without ground spoilers or normal braking. If the Aux System remains functional, landing and braking operations will be normal. Gulfstream's reference to Crew Resource Management in their submission, in part, stated: Gulfstream has refocused our efforts to promote proper Crew Resource Management among all of its crews. Gulfstream will encourage Flight Safety International, its principle flight training resource for customer aircrews, to incorporate lessons learned from this accident into its training regimen. PneuDraulics reference to Proposed Safety Recommendations in their submission, in part, stated: After a review of the Gulfstream GV-SP hydraulic system architecture, it seems that a fundamental improvement to the hydraulic system on the Nose Wheel section of the aircraft would be the addition of a velocity or volumetric hydraulic fuse. This component is designed to minimize the loss of hydraulic fluid in the event of a line break downstream of such a device. In fact, the GV-SP does have hydraulic volumetric fuses as part of the main landing gear brake system to protect against hydraulic system pressure loss should a similar incident happen in the main landing gear area. The NTSB IIC was advised by the FAA of an incident in San Juan, Puerto Rico, on December 20, 2001, involving a Gulfstream V. That airplane's hydraulic fluid leaked during the flight and the airplane's four main tires blew out when the flight crew used the airplane's emergency brakes to stop the airplane on the runway. A service difficulty report of an incident on July 22, 2001, indicated that a Gulfstream V had a nose landing gear swivel assembly rupture. The report indicated that ruptured swivel had accumulated 520 hours and 273 cycles. According to Gulfstream, the hydraulic input to the nose wheel steering system was redesigned to include PneuDraulics modifications to the nose wheel swivel assembly. The executive summary in NTSB Aircraft Accident Report NTSB/AAR-11/01, Crash During Attempted Go-Around After Landing, East Coast Jets Flight 81, Hawker Beechcraft Corporation 125-800A, N818MV, Owatonna, Minnesota, July 31, 2008, in part, stated: On July 31, 2008, about 0945 central daylight time, East Coast Jets flight 81, a Hawker Beechcraft Corporation 125-800A airplane, N818MV, crashed while attempting to go around after landing on runway 30 at Owatonna Degner Regional Airport, Owatonna, Minnesota. The two pilots and six passengers were killed, and the airplane was destroyed by impact forces. The nonscheduled, domestic passenger flight was operating under the provisions of 14 Code of Federal Regulations Part 135. An instrument flight rules flight plan had been filed and activated; however, it was canceled before the landing. Visual meteorological conditions prevailed at the time of the accident. The National Transportation Safety Board determines that the probable cause of this accident was the captain's decision to attempt a go-around late in the landing roll with insufficient runway remaining. Contributing to the accident were (1) the pilots' poor crew coordination and lack of cockpit discipline; (2) fatigue, which likely impaired both pilots' performance; and (3) the failure of the Federal Aviation Administration (FAA) to require crew resource management (CRM) training and sta