Citation Excel (C560XL)
Flight Crew Air Transport Pilot (ATP)
Confusion
Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Returned To Clearance; Flight Crew Overcame Equipment Problem
Aircraft; Company Policy; Procedure; Human Factors
We were assigned the RUUDY4 RNAV departure; runway 24; at TEB. I was the pilot not flying. The pilot flying briefed the departure thoroughly including that he would do a noise abatement climb; stay below 200 KTS and use the autopilot. I concurred. The attitude selector was set for 1;500 and the flight director was used in NAV (LNAV) mode. After takeoff and gear up; at 500 FT the pilot flying called for autopilot ON. I pointed out that the limitation for the autopilot is 1;000 FT and said I would turn it on at 1;000 FT. He indicated that he believed that was an enroute limitation; not a takeoff limitation. At 1;000 FT I said 'autopilot coming on' and pressed the switch; but I saw on the PFD that the autopilot was not engaged. I called out 'the autopilot did not engage; you will have to level off.' During the level off we bracketed the 1;500 FT altitude by about 170 FT above to 50 FT below and then established at 1;500. After flaps were up we engaged the autopilot successfully and flew the rest of the departure. ATC did not comment on the attitude excursion and; in fact; cleared us up to 7;000 almost immediately. We later discussed why the difference in understanding of the 1;000 FT autopilot limitation. The pilot flying based his understanding on having previously flown the CJ3 which has a specific 'takeoff' altitude limitation for the autopilot. I believe the confusion interrupted his planned execution of the takeoff and the failure of the autopilot to engage compounded that and added a momentary high workload. We agreed to consult an objective source to resolve the different interpretations of the limitations. I consulted a company check airman. He said that he used 1;000 FT as a takeoff limitation for the autopilot but he agreed that the use of 'ENROUTE' to label the limitation was potentially confusing. We consulted the Flight Safety; Excel Program Manager and several days later received this reply: '...these limitations are given to Cessna by the avionics manufacturer; and for some reason our aircraft models do not have that limitation. It could be due to a lack of testing data - we do not know for sure. The safest route is to go with 1;000 FT minimum altitude; and not engage the autopilot prior to that on the climb out. That's all we can say for sure - we can't advise you to engage the autopilot earlier since it's not specified in the limitations where that should be after takeoff. It would be helpful if this could be addressed more specifically for the entire XL/XLS pilot group so a reoccurrence in a similar situation could be avoided if there are other pilots that have different interpretations.
A CE560 flight crew disagrees on what altitude the autopilot can be engaged at (500 or 1;000 FT) after takeoff on the RUUDY 4 at TEB. When the autopilot will not engage at 1;000 FT a rapid manual level off produces oscillations above and below 1;500 FT. The autopilot engages normally once level at 1;500 FT.