Narrative:

Incident aircraft (ia) departed under IFR control; weather 200 ft AGL ceilings and 3/4 SM visibility. Ia lifted off the runway normally. At 100 ft AGL incident pilot (ip) selected the landing gear switch to the up position. Immediately upon initiation of the retraction cycle the ia began to oscillate in pitch and roll becoming increasingly violent. The ip; unsure of nature of the emergency and entering IMC; attempted to maintain sight of runway 33 for an immediate landing. Unable to do so because of poor visibility; ip [advised] tower and continued to climb heading 130. The ip selects the landing gear into the down position upon recognition of erratic landing gear position lights. Landing gear successfully extends into the down and locked position and ip elects to keep the gear in this position for the remainder of flight. Tower switches ip to approach control. Ip checks in with approach control and coordinates maneuvering airspace block altitude 1500 MSL-2500 MSL heading 090 to troubleshoot. Ip requests normal vectors for ILS 24. Ip lands ia with normal gear down and locked indications and no abnormal events.there is currently no procedure for pilot preflight of the hydraulic reservoir plug due to its location and the required removal of panels to access that component. Because of this; it is impractical to recommend additional aircrew preflight items. Recommend a review of the execution of policies and procedures required to render an aircraft as 'safe for flight' following a maintenance action.

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Original NASA ASRS Text

Title: A C402 departed IMC for a ferry flight; but upon raising the landing gear the aircraft developed violent pitch and roll oscillations. After lowering the landing gear; aircraft control returned so the pilot returned to the departure airport where a hydraulic reservoir anomaly was discovered.

Narrative: Incident Aircraft (IA) departed under IFR control; weather 200 ft AGL ceilings and 3/4 SM visibility. IA lifted off the runway normally. At 100 ft AGL Incident Pilot (IP) selected the landing gear switch to the up position. Immediately upon initiation of the retraction cycle the IA began to oscillate in pitch and roll becoming increasingly violent. The IP; unsure of nature of the emergency and entering IMC; attempted to maintain sight of runway 33 for an immediate landing. Unable to do so because of poor visibility; IP [advised] tower and continued to climb heading 130. The IP selects the landing gear into the down position upon recognition of erratic landing gear position lights. Landing gear successfully extends into the down and locked position and IP elects to keep the gear in this position for the remainder of flight. Tower switches IP to Approach Control. IP checks in with Approach Control and coordinates maneuvering airspace block altitude 1500 MSL-2500 MSL heading 090 to troubleshoot. IP requests normal vectors for ILS 24. IP lands IA with normal gear down and locked indications and no abnormal events.There is currently no procedure for pilot preflight of the hydraulic reservoir plug due to its location and the required removal of panels to access that component. Because of this; it is impractical to recommend additional aircrew preflight items. Recommend a review of the execution of policies and procedures required to render an aircraft as 'safe for flight' following a maintenance action.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.