ATL05IA116

According to the captain, the flight and landing were uneventful, and the airplane was parked at the gate. The parking brake was set, the nosewheel steering was shut off, and the seatbelt sign was turned off. The ground power unit was connected, the green "AVAIL" light on the overhead panel illuminated, and the captain selected ground power. He stated he then turned off the No. 2 generator, and, at that "exact moment ... we observed a momentary flash of cabin and cockpit lights, and ... simultaneously ... the nose gear collapsed." Examination of the airplane's nose landing gear selector valve revealed slack in the lock wire on the spanner end cap, and the spanner end cap was backed off. Test bench examination of the unit revealed an internal hydraulic fluid leak, and disassembly examination revealed glyd rings No. 1 and No. 4 were damaged. The lock wire, end cap, and glyd ring conditions were the subject of two previous service bulletins, one from the valve manufacturer, Tactair, and one from the airplane manufacturer, Bombardier. The service bulletins stated glyd ring damage and the associated hydraulic leak had occurred in some improperly assembled valves, and the damage condition, combined with an interruption of electrical power to the airplane, had resulted in the collapse of the nose landing gear of some affected airplanes. Tactair had issued its service bulletin dated March 12, 2003, effective for valve serial numbers 0001 to 0645; the incident airplane's nose landing gear selector valve was serial number 550. Bombardier had issued a service bulletin dated May 29, 2003, with Revision "A" dated June 12, 2003, that directly referenced the Tactair service bulletin and was distributed to each airplane operator. The Bombardier service bulletin, however, incorrectly listed its effectivity; it stated the service bulletin applied to Bombardier airplane serial numbers 7045 thru 7067 and 7069 thru 7189. The incident airplane was Bombardier serial number 7192, and selector valve serial number 550 was original equipment for that airplane. The service bulletin is being revised.

On June 28, 2005, at 1150 eastern daylight time, a Canadair (Bombardier) CL-600-2B19, N623BR, registered to State Street Bank & Trust Co. of CT NA Trustee and operated by FLYI, Inc., as Independence Air Flight 1784, collapsed the nose landing gear while parked at the gate at Piedmont Triad International Airport, Greensboro, North Carolina. The scheduled domestic air carrier flight was operated under the provisions of Title 14 CFR Part 121 with an instrument flight rules plan filed. Visual meteorological conditions prevailed. The airline transport pilot-certificated captain, the airline transport pilot-certificated first officer, and 33 passengers reported no injuries; the flight attendant and 1 passenger reported minor injuries. The airplane sustained minor damage. The flight departed Washington Dulles International Airport, Dulles, Virginia, about 1040.

According to the captain, the flight and landing were uneventful, and the airplane was taxied to gate 23 and parked normally. He stated the parking brake was set, the nosewheel steering was shut off, and the seatbelt sign was turned off. He stated the flight attendant opened the main cabin door, and he waited for the ground personnel to connect the ground power to the airplane. The captain stated the ground personnel signaled that ground power was connected, the green "AVAIL" light on the overhead panel illuminated, and he selected ground power. He stated he then turned off the No. 2 generator, and, at that "exact moment ... we observed a momentary flash of cabin and cockpit lights, and the EICAS displayed several caution messages. Simultaneously with this, the nose gear collapsed."

The flight attendant reported she and several passengers were standing in the aisle waiting for the jetway when the front of the airplane fell. The flight attendant checked on the passengers, and the flight attendant and ground crew assisted the passengers in exiting the airplane through the main cabin door via the stairs.

The airplane sustained crush damage to the nose landing gear doors, dent and crush damage to the underside of the forward fuselage immediately forward and aft of the nose landing gear, and buckling of the skin up through the ground power connection box.

Examination and testing of the airplane's nose landing gear proximity sensing electronic unit (PSEU) revealed no evidence of malfunction. Visual examination of the airplane's nose landing gear selector valve, Tactair Fluid Controls, Inc., part number 750006000, revealed the lock wire on the spanner end cap showed slack, and the spanner end cap was backed off more than 0.030 inches. Test bench examination of the unit revealed an internal hydraulic fluid leak, and disassembly examination revealed glyd rings No. 1 and No. 4 were damaged.

A review of publications revealed Tactair Fluid Controls, Inc., issued Service Bulletin SB750006000-1 Rev N/C, dated March 12, 2003, effective for selector valve part number 750006000, serial numbers 0001 to 0645. The incident airplane's nose landing gear selector valve was Tactair serial number 550. According to the service bulletin, Section 1B states, "(1) A number of 750006000 selector valves have been assembled with incorrectly installed lockwire on the spanner end cap ... . (2) ... Some in-service valve failures have occurred which have led to nose landing gear partial collapse when the following conditions occur: a. The glyd seal of the spool and sleeve assembly is cut ... this is caused by the backing off of the spanner end cap due to incorrect lock wire installation ... . b. The [airplane] is on the ground and the ... master battery switch is turned off while no other power is applied to the [airplane] and while there is still residual pressure in the hydraulic system No. 3 accumulator." The service bulletin provided inspection instructions for the identification and removal of potentially affected units.

A review of publications revealed Bombardier Aerospace issued Service Bulletin SB601R-32-090, dated May 29, 2003, with Revision "A" dated June 12, 2003. According to the service bulletin header, it was distributed by Bombardier Regional Aircraft Division to "each affected operator." The service bulletin recommended the inspection of the end caps of nose landing gear selector valves serial numbers 0001 to 0645, however, Section 1A, "PLANNING INFORMATION, Effectivity," states, "(1) Aircraft Affected: Service Bulletin: CL-600-2B19 Canadair Regional Jet (CRJ) Aircraft Serial Numbers 7045 thru 7067 and 7069 thru 7189." The incident airplane was Bombardier serial number 7192.

Review of manufacturing and maintenance records revealed nose landing gear selector valve serial number 550 was originally manufactured by Kaiser Fluid Technologies and delivered in February 1997. The unit was originally installed on the incident airplane, and the unit accumulated approximately 19,199.86 operating hours and 16,242 cycles.

Review of the data from airplane's flight data recorder revealed an electrical power interruption of 6 seconds immediately preceded the collapse of the nose landing gear.