Narrative:

Preparation for the flight proceeded normally. At vr, the nose gear door light illuminated, the yaw damper and mach trim disconnected, the instrument miscompare annunciator illuminated, the copilot's and standby airspeed indicators became erratic, the copilot's and standby altimeters became sluggish, and the copilot's ivsi became twitchy. After a positive rate had been idented using the pilot's instruments and visual cues the gear was retracted and the climb out continued. After re-engaging the yaw damper and identing the numerous failures, my copilot indicated to the local controller that we would like to return for landing due to an improper landing gear door indication. An emergency was not declared as we were not experiencing aircraft control difficulties and the WX was quite favorable. During the subsequent vectoring, we ran the checklists that pertained to the gear indication and instrument anomalies. As we were doing these it dawned on us that cause of the failures were indeed related. The oxygen pressure indicator is located in front of the pitot static probe on the right side of the aircraft. This pressure gauge is behind a small door with 2 flush latches. Also located behind this door is a small lever that is used to release the nose gear doors for preflight. The door must be open and the nose gear release must still be in the extended position. The landing was uneventful. And upon inspection of the oxygen gauge door, we indeed found it to be open and the nose gear door release was in the extended position. The position of the nose gear door release allowed the nose gear door to open uncommanded when the airflow over it was adequate to repos it during the rotation. Being out of sequence with the other door, it would not retract. The oxygen pressure gauge door in the open position disrupts airflow in the vicinity of the pitot/static probe rendering the instruments gathering information from them to be unreliable. These instrument failures resulted in the miscompare indications and disconnection of the yaw damper and mach trim and air data failure. We repositioned the nose gear door release lever and closed and latched the oxygen pressure gauge door. The nose gear doors were sequenced and cycled. The obvious culprit was the fact that the nose gear release lever was left extended and the oxygen pressure gauge door was not properly closed and latched. During all other preflts, these items had not been missed, up to now. Putting a greater emphasis on the details of the preflight would have likely prevented this event. Callback conversation with reporter revealed the following information: the reporter idented the aircraft as a CL603A. The first officer did the preflight walkaround while the captain did the 'office work.' this also entails contacting the passenger, obtaining supplies, coffee, services and food. The captain said that, 'in his mind the preflight was already accomplished' and that 'he normally takes a close look at the aircraft.' he further stated that, 'this day he had not.' the right side of the aircraft was in the shade and the sun was presenting some glare so he did not note the door lever release handle protruding from the aircraft's side. The handle has to be inside the frame of the aircraft to close that door. This event was all the more embarrassing to him since there were passenger on board.

Google
 

Original NASA ASRS Text

Title: A CL603A CHALLENGER HAS TO RETURN LAND AT LAX WHEN THE NOSE GEAR DOOR WARNING LIGHT AND NUMEROUS ACFT INST READINGS INDICATED MULTIPLE AIR DATA PROBS.

Narrative: PREPARATION FOR THE FLT PROCEEDED NORMALLY. AT VR, THE NOSE GEAR DOOR LIGHT ILLUMINATED, THE YAW DAMPER AND MACH TRIM DISCONNECTED, THE INST MISCOMPARE ANNUNCIATOR ILLUMINATED, THE COPLT'S AND STANDBY AIRSPD INDICATORS BECAME ERRATIC, THE COPLT'S AND STANDBY ALTIMETERS BECAME SLUGGISH, AND THE COPLT'S IVSI BECAME TWITCHY. AFTER A POSITIVE RATE HAD BEEN IDENTED USING THE PLT'S INSTS AND VISUAL CUES THE GEAR WAS RETRACTED AND THE CLBOUT CONTINUED. AFTER RE-ENGAGING THE YAW DAMPER AND IDENTING THE NUMEROUS FAILURES, MY COPLT INDICATED TO THE LCL CTLR THAT WE WOULD LIKE TO RETURN FOR LNDG DUE TO AN IMPROPER LNDG GEAR DOOR INDICATION. AN EMER WAS NOT DECLARED AS WE WERE NOT EXPERIENCING ACFT CTL DIFFICULTIES AND THE WX WAS QUITE FAVORABLE. DURING THE SUBSEQUENT VECTORING, WE RAN THE CHKLISTS THAT PERTAINED TO THE GEAR INDICATION AND INST ANOMALIES. AS WE WERE DOING THESE IT DAWNED ON US THAT CAUSE OF THE FAILURES WERE INDEED RELATED. THE OXYGEN PRESSURE INDICATOR IS LOCATED IN FRONT OF THE PITOT STATIC PROBE ON THE R SIDE OF THE ACFT. THIS PRESSURE GAUGE IS BEHIND A SMALL DOOR WITH 2 FLUSH LATCHES. ALSO LOCATED BEHIND THIS DOOR IS A SMALL LEVER THAT IS USED TO RELEASE THE NOSE GEAR DOORS FOR PREFLT. THE DOOR MUST BE OPEN AND THE NOSE GEAR RELEASE MUST STILL BE IN THE EXTENDED POS. THE LNDG WAS UNEVENTFUL. AND UPON INSPECTION OF THE OXYGEN GAUGE DOOR, WE INDEED FOUND IT TO BE OPEN AND THE NOSE GEAR DOOR RELEASE WAS IN THE EXTENDED POS. THE POS OF THE NOSE GEAR DOOR RELEASE ALLOWED THE NOSE GEAR DOOR TO OPEN UNCOMMANDED WHEN THE AIRFLOW OVER IT WAS ADEQUATE TO REPOS IT DURING THE ROTATION. BEING OUT OF SEQUENCE WITH THE OTHER DOOR, IT WOULD NOT RETRACT. THE OXYGEN PRESSURE GAUGE DOOR IN THE OPEN POS DISRUPTS AIRFLOW IN THE VICINITY OF THE PITOT/STATIC PROBE RENDERING THE INSTS GATHERING INFO FROM THEM TO BE UNRELIABLE. THESE INST FAILURES RESULTED IN THE MISCOMPARE INDICATIONS AND DISCONNECTION OF THE YAW DAMPER AND MACH TRIM AND AIR DATA FAILURE. WE REPOSITIONED THE NOSE GEAR DOOR RELEASE LEVER AND CLOSED AND LATCHED THE OXYGEN PRESSURE GAUGE DOOR. THE NOSE GEAR DOORS WERE SEQUENCED AND CYCLED. THE OBVIOUS CULPRIT WAS THE FACT THAT THE NOSE GEAR RELEASE LEVER WAS LEFT EXTENDED AND THE OXYGEN PRESSURE GAUGE DOOR WAS NOT PROPERLY CLOSED AND LATCHED. DURING ALL OTHER PREFLTS, THESE ITEMS HAD NOT BEEN MISSED, UP TO NOW. PUTTING A GREATER EMPHASIS ON THE DETAILS OF THE PREFLT WOULD HAVE LIKELY PREVENTED THIS EVENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR IDENTED THE ACFT AS A CL603A. THE FO DID THE PREFLT WALKAROUND WHILE THE CAPT DID THE 'OFFICE WORK.' THIS ALSO ENTAILS CONTACTING THE PAX, OBTAINING SUPPLIES, COFFEE, SVCS AND FOOD. THE CAPT SAID THAT, 'IN HIS MIND THE PREFLT WAS ALREADY ACCOMPLISHED' AND THAT 'HE NORMALLY TAKES A CLOSE LOOK AT THE ACFT.' HE FURTHER STATED THAT, 'THIS DAY HE HAD NOT.' THE R SIDE OF THE ACFT WAS IN THE SHADE AND THE SUN WAS PRESENTING SOME GLARE SO HE DID NOT NOTE THE DOOR LEVER RELEASE HANDLE PROTRUDING FROM THE ACFT'S SIDE. THE HANDLE HAS TO BE INSIDE THE FRAME OF THE ACFT TO CLOSE THAT DOOR. THIS EVENT WAS ALL THE MORE EMBARRASSING TO HIM SINCE THERE WERE PAX ON BOARD.

Data retrieved from NASA's ASRS site as of July 2007 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.