Dash 8-100
Aircraft Equipment Problem Less Severe
Aircraft Equipment Problem Dissipated; Flight Crew Landed As Precaution; Flight Crew Returned To Departure Airport; General Maintenance Action
Aircraft
The nose gear attempted to retract during initial climb immediately after liftoff; even though the gear handle was never moved from the down position the entire flight. A repetitive banging was heard; from the flight deck only; of the nose gear attempting to retract; presumably into the still closed nose gear door. The nose gear red unsafe light and the red in-transit light on the gear selector illuminated and cycled repeatedly on and off; in conjunction with the banging we heard. The cycling stopped on it's own; leaving only all three green lights illuminated. We elected to leave the landing gear selector in the down position. We elected to return to field and had the emergency equipment standing by in the event of a gear collapse. As a precaution; we elected to perform the alternate gear extension procedure under the assumption that the gear HAD malfunctioned even though it was indicating only 3 green lights at the time; and that if the nose gear attempted to retract itself again; or received a false signal to do so; that relieving the hydraulic pressure in the lines would prevent a possible nose gear collapse. We landed after briefing the flight attendant and the passengers. A signal for brace was not deemed necessary; because the gear was indicating down and locked and because we complied with the Alternate Landing Gear Extension procedure. We taxied to the gate.We left the gear selector down. We performed the After Takeoff checklist with the exception of landing gear. We maintained approximately 150 knots until it was time to perform the alternate landing gear extension procedure. (The amber advisory lights for the landing gear doors were extinguished prior to the alternate landing gear extension procedure). We performed the alternate landing gear extension procedure. We notified the flight attendant and then the passengers. We landed and taxied back to the gate after the trucks looked for obvious damage; finding none.
The reporter stated that no damage to the nose gear door was evident during post flight. The reporter believes that an electrical short circuit may have caused the anomaly and may be related to aircraft age. He also believes that the emergency extension system would have allowed for safe gear extension had the cycling not stopped on its own.
On initial climb out right after rotation; the amber gear handle light; red nose gear light; and the green nose gear down and locked light started to flash on and off with a noticeable banging sound coming from the nose gear wheel well. It appeared as if the nose gear was trying to retract with the gear handle in the down position. I informed the captain that I was not going to retract the landing gear. He agreed that we should leave the gear down. We continued the climb; retracted the flaps and set the power to maintain appropriate airspeed with the gear down. After about 30 seconds; the flashing and noise stopped. The gear showed all down and green on main and backup indicators; however; we were concerned that this problem might return as we were returning back to the field to land. After discussing the situation; we elected to declare an emergency; and to perform an emergency gear extension to take the hydraulic pressure off the system and insure that the nose gear would stay down. We contacted both dispatch and maintenance to discuss the situation. We performed the alternate gear extentsion and landed without further incident. After checking over systems on the ground; we taxied to the gate.
DHC8 flight crew experienced a banging noise and flashing nose gear lights at rotation with the landing gear handle in the down position. After 30 seconds the banging stopped and the crew elected to perform an emergency landing gear extension and return to the departure airport. It appeared to the crew that the nose landing gear was repeatedly attempting to retract with the landing gear handle down.