N662QSTextron Aviation 680A · 2021

On January 13, 2013, at 1818 eastern standard time, the flight crew of a Cessna 560XL, N662QS, operated by NetJets Aviation, Inc., experienced in-flight stiffness of the elevator controls while climbing through FL350 near Debary, Florida. Both airline transport pilots and both passengers were not injured, and the airplane was not damaged. Instrument meteorological conditions prevailed, and the airplane was operating on an instrument flight rules flight plan. The flight originated from St. Lucie County International Airport (FPR), Fort Pierce, Florida at 1752, and was destined for Dekalb-Peachtree Airport (PDK), Atlanta, Georgia. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91, Subpart K.

The flight departed from FPR uneventfully and was climbing to a planned cruise altitude of FL380. Just prior to entering a cloud layer at FL320, the flight crew activated the engine and wing anti-ice systems, as well as the pneumatic tail de-ice system. As the airplane climbed through FL350 at a rate of 1,000 feet per minute (fpm) and with the autopilot engaged, the airplane pitched nose-down and entered a 400-fpm descent. The flight crew then disconnected the autopilot, assumed manual control of the airplane, and leveled at FL350.

Both crewmembers noted that "excessive" force was required to change the pitch of the airplane, and subsequently notified air traffic control of the situation. The crew then requested a descent, and during the descent noted that the manual and electric pitch trim systems appeared to function normally; but that both trim and manual elevator control inputs would result in an exaggerated pitch response from the airplane. Upon descending through FL180, the crew reported that something "broke loose" and the elevator controls began to respond normally. The crew subsequently re-engaged the autopilot and continued to PDK uneventfully.

The incident airplane was manufactured in 2002, and its most recent phase inspection was completed on January 13, 2013 at an airframe total time of 8,990 hours of operation.

Following incidents in 2010 and 2011 (see NTSB cases ERA11IA184 and CEN11IA087), the airframe manufacturer issued two mandatory service bulletins that detailed the procedures for installing drain holes in the lower aft portion of the fuselage. These drains were implemented in order to provide a path for accumulated moisture from the aft tailcone area to exit. A seal was also added to reduce the amount of water entering the tailcone stinger. In April 2012, both service bulletins were incorporated into a Federal Aviation Administration (FAA) Airworthiness Directive (AD), AD 2012-06-01. Review of maintenance records for the incident airplane revealed that the Service Bulletins and Airworthiness Directive were complied with shortly after each of their respective issuances.

About that time, the operator also implemented a one-time procedure (TC-5XL-53-110306) to inspect and clean each of the fuselage bilge drains. The procedure directed maintenance technicians to inspect for the presence of debris that would clog the drains and for the presence of stains that would indicate the presence of previous standing water. The inspection began at the aft canted bulkhead, near fuselage frame station (FS) 573, and proceeded forward to the fuselage drain located a fuselage station FS373. The procedure was completed on the incident airplane in May 2011.

Field Examination

Two days after the event, the airplane was examined while on the ground at PDK. Utilizing the fuselage drain inspection and cleaning procedure developed by the operator, the empennage of the airplane was examined. The examination documented the following at each respective fuselage station drains:

FS573 No obstructions, some grass noted.

FS550 Drain 50% obstructed, tidal mark observed 5 inches above lowest point of belly on aft side of frame.

FS544 Drain 100% obstructed, tidal mark at 8 inches on aft side of frame with evidence of forward spillage, 1/4-inch of standing water.

FS528 No obstructions, other debris noted in general area, tidal staining exceeded height of frame.

FS512 Drain 40% obstructed, 1/2-inch tidal mark.

FS496 Drain 100% obstructed.

FS479 Drain 100% obstructed, 1 1/2-inch tidal mark.

FS462 Debris accumulation to within 1/8-inch of control cable cutout, other minor accumulation of debris to the right and left, standing water noted.

FS460 Drain 100% obstructed with standing water to 1/4-inch, at control cable cutout.

FS449 Elevator cable pulley mounting location. Pulleys appeared visibly saturated with water with beads of water present.

FS421 Drain 60% obstruction, 1/4-inch tidal mark.

In preparing the airplane for return to service, the operator performed additional inspections of the elevator control system including a function check of each elevator cable pulley. The mechanics performing the inspections subsequently found that the pulleys installed at FS528 were not free to rotate, and that their bearings had seized. The pulleys from FS528, water-saturated pulleys from FS449, a pulley from FS438, along with a sample of the debris found obstructing some of the fuselage drains were forwarded to the NTSB Materials Laboratory for further examination.

The mechanics further noted that the tailcone stinger seals, which were installed in compliance with Cessna Service Bulletin SB650XL-53-16 in order to reduce the amount of water entering the stinger, were not trimmed to overlap in accordance with the service bulletin.

Laboratory Examination

The pulleys recovered from FS528, FS449, and FS438 were examined in the NTSB Materials Laboratory, and compared with new exemplar pulleys provided by the airframe manufacturer. The left pulley recovered from FS528 displayed partial staining of its phenolic material, with a distinct line separating the stained and non-stained areas. Both FS528 pulleys' grooves displayed a shiny, smooth appearance. The bearings of the pulleys were not free to rotate, and exhibited radially oriented stains emanating from the bearing on both sides. Deposits that could be removed with a fingernail were also noted around the bearing seals. The bearings were subsequently disassembly, and the interior bearing balls and races exhibited corrosion.

The pulleys recovered from FS449 appeared uniformly darker in color than the pulleys from FS528 and the exemplar pulleys, and also felt damp when handled. The bearings rotated smoothly contained grease. The dampness was swabbed from both pulleys and examined using Fourier-Transform Infrared Spectroscopy and found to be water and an unidentified silicon-based product.

Examination of the obstructing debris sample revealed the presence mostly unknown fibrous material with gray, black, orange, and red filaments. Also present were beetles, a rivet shank, other rivet pieces with shank, a portion of rubber seal, a cotter pin, a portion of a nylon wire tie, a washer, and a piece of twisted lock wire.

Following the incident, the operator updated their approved aircraft inspection program to incorporate a recurring fuselage bilge drain inspection and cleaning every 300 flight hours. The airframe manufacturer also drafted an update to the Cessna Model 560XL Maintenance Manual introducing a visual inspection and cleaning of the tailcone and bilge areas that would recur at 600 hour/12 calendar months or 1,200 hours/24 calendar months.

On May 28, 2010, about 1220 eastern daylight time, a Cessna 560XL, N662QS, incurred minor damage when the main cabin door opened while in flight, shortly after takeoff from Westchester County Airport (HPN), White Plains, New York. The certificated airline transport pilot-rated captain, first officer, and the two passengers were not injured. Visual meteorological conditions prevailed, and the flight was operating on an instrument flight rules flight plan. The corporate flight was destined for Nantucket Memorial Airport (ACK), Nantucket, Massachusetts. The flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91K.

The captain and first officer were interviewed separately by Federal Aviation Administration inspectors following the incident. Both pilots were qualified to act as captains in the Cessna 560XL, and their roles for the incident flight were previously defined by the operator. The captain was also designated as the pilot flying, while the first officer was designated as the pilot not flying (or pilot monitoring). During his safety briefing with the passengers after boarding, the first officer closed the cabin door. The first officer remembered rotating the door locking handle, but could not recall the direction he rotated it. He also could not recall looking at the door post locking indicator lights or the cockpit indicator.

After completing the required checklists, the crew taxied the airplane "slowly" toward runway 16, and was delayed before being cleared to depart. During the delay, the captain focused his attention on the air traffic control communications and formulated a mental picture of the traffic in the area of the airport. Just after takeoff, the captain recalled that he heard the cabin door leaking and the first officer observed that the DOOR SEAL/CABIN DOOR annunciator light was illuminated. When asked, the first officer did not recall the master caution annunciator illuminating.

The crew requested and was cleared to return to runway 16. While on the downwind leg of the traffic pattern, the main cabin door opened. The crew subsequently declared an emergency, and landed uneventfully with the main cabin door open.

According to the Cessna 560XL maintenance manual, the cabin door was located on the left forward side of the airplane. The door was hinged at its bottom, opened outward, and was equipped with a pre-catch mechanism, which assisted in holding the door closed before the locking mechanism was engaged. Eight locking pins were mechanically linked to internal and external lock/unlock handles, with three locking pins located in each side of the door and two locking pins at the top of the door. When actuated by the lock/unlock handle, the door pins extended into the door frame sockets to secure the door in the closed position.

Six electrical switches monitored the door's closed and locked position, with four switches actuated by the upper and lower side locking pins, one switch monitoring the door vent, and one switch monitoring the door locking mechanism's position. The switches were electrically connected to the warning annunciator panel in the cockpit, and only when each of the six switches was closed, would the CABIN DOOR annunciator extinguish. Should any of the six switches toggle from locked to unlocked, the CABIN DOOR and MASTER CAUTION annunciator would illuminate. Resetting the MASTER CAUTION would extinguish the MASTER CAUTION annunciator, but the CABIN DOOR annunciator would remain illuminated. A DOOR LOCKS panel was also located on the cabin door post, and was equipped with six light-emitting diodes to indicate the position of the door locks, door handle, and vent door. Each light illuminated when its respective switch sensed that a component was in the unlocked position and extinguished when its respective component was in the locked or closed position. When the door was closed and locked, the door vent light extinguished after several seconds and the vibration from the closing vent could be felt near the bottom of the cabin door. Additionally, nine indicator windows were placed throughout the door, so that when the door was properly closed and locked, a phosphorescent green flag was clearly visible through each respective indicating window.

The cockpit annunciator panel provided numerous system notifications to the crew. The CABIN DOOR annunciator light (colored yellow) was located on the bottom of three rows of annunciator lights, on the sixth column from the right. The GROUND IDLE annunciator light (colored white) was also located on the sixth column from the right, above the CABIN DOOR annunciator light, on the first row of annunciator lights. The GROUND IDLE annunciator would normally be illuminated after engine start and while the airplane was taxiing to the runway, and would be the only annunciator illuminated just prior to takeoff.

The captain held an airline transport pilot certificate with ratings for airplane single and multi-engine land. The pilot's most recent first-class medical certificate was issued in July 2009. He reported 7,459 total hours of flight experience, 1,737 hours of which were in the incident airplane make and model.

The first officer held an airline transport pilot certificate with ratings for airplane single and multi-engine land. His most recent first-class medical certificate was issued in April 2010. He reported 5,964 total hours of flight experience, 1,432 hours of which were in the incident airplane make and model.

At 1156 recorded weather at HPN included calm winds, a broken ceiling at 3,200 feet, 10 statute miles visibility, temperature 19 degrees C, dew point 11 degrees C, and an altimeter setting of 29.98 inches of mercury.

The airplane was equipped with a cockpit voice recorder, which was retained and auditioned in the NTSB Vehicle Recorders Laboratory. Audition of the recorder revealed a series of events consistent with the flight crews' statements. While completing the engine start checklist, the crew noted 'cabin door closed' and 'lights out'. Shortly thereafter, the flight crew noted that the annunciators and instruments were checked. The flight crew completed the runway items checklist and noted "lights, heat, and lights out."

Two FAA inspectors examined the main cabin door after the incident. According to the inspectors, the door had been over-extended when it opened in-flight, and had scraped against the runway during the landing. Damage to the door precluded closing the door normally, though the door could be opened and closed with force provided by individuals on the inside and outside. Detailed mechanical inspection of the door revealed that the pre-catch mechanism appeared to operate normally, and there was no visual indication of any door locking pin or pin socket failure. The annunciator lights on the DOOR LOCK panel and the CABIN DOOR annunciator functioned normally, including illumination of the MASTER CAUTION annunciator when the door was opened. The inspectors further noted that if electrical power (from a the airplane's battery or a power cart) was applied to the airplane with the cabin door open, the CABIN DOOR annunciator remained steadily illuminated until the door was closed. The illumination of a MASTER CAUTION annunciator, accompanied by a blinking CABIN DOOR annunciator, would only occur after the door was closed, locked, then unlocked and reopened.

According to the operator's Expanded Normal Procedures, Engine Start checklist, both of the pilots were to perform the following actions:

Cabin Door.................Closed/Light Out

-Close and latch cabin door

-Verify cabin door pin indicators are visible

-Verify cabin door red LED lights are extinguished

-Verify the cockpit Cabin Door annunciator is extinguished.

The Runway Items flow checklist procedure required the pilot monitoring to ensure that all annunciator lights were extinguished with the exception of GROUND IDLE after being cleared for takeoff.