Birmingham, AL, USA
N498AB
CESSNA 560XL
During approach and landing, the pilots noted that the airplane had stiff rudder operation. A postflight examination of the airplane found ice in its tailcone stinger, through which the rudder and elevator control cables run. Further investigation discovered that other Cessna 560XL airplanes had encountered the same problem. The design of the airplane was such that water could enter the tailcone, collect there, and freeze around the rudder cables during operations in subfreezing temperatures. The manufacturer had issued a service letter (SL) in 2005 to add a drain hole in the tailcone stinger for in-service airplanes and added a drain hole to production airplanes; this incident airplane had a drain hole in its tailcone that was consistent with the SL. Therefore, the drain hole specified in the SL was not sufficient to correct the problem. In addition, the investigation discovered that some production airplanes had drain holes that were smaller than the size specified in the SL. The manufacturer subsequently issued an alert service letter (ASL) in January 2011 to inspect the existing drain holes to ensure they were the right size, seal an existing drain hole, and add another drain hole in the aft canted bulkhead; however, in March 2011, an airplane modified in accordance with the ASL experienced stuck rudder controls; ice and water were found in its tailcone stinger. The manufacturer subsequently issued a mandatory service bulletin (SB) in October 2011 that specified additional modifications intended to reduce the amount of moisture that can enter the tailcone stinger and to improve the drainage. The Federal Aviation Administration (FAA) district office that oversees the production certification of the Cessna 560XL and the manufacturer's issuance of associated SLs and SBs did not detect the improper-sized holes on some production airplanes. The manufacturer subsequently implemented a specific inspection to verify the drain hole installation on production airplanes, and the FAA has followed up.
On December 13, 2010, about 0757 central standard time, a Cessna 560XL, N498AB, operated by Executive Jet Management, Inc., sustained a loss of rudder authority during landing at the Birmingham-Shuttlesworth International Airport (BHM), near Birmingham, Alabama. The two pilots and one passenger were not injured and the airplane was not damaged. Visual meteorological conditions prevailed. The flight was operating on an activated instrument flight rules flight plan. The non-scheduled domestic passenger flight was conducted under 14 Code of Federal Regulations Part 135. The flight departed from the Teterboro Airport (TEB), near Teterboro, New Jersey, about 0442, and was destined for BHM. According to the operator, the entire flight was normal until the autopilot and yaw damper were disconnected on final approach to BHM. The flight crewmembers discovered that the rudder pedals were unusually stiff, which required that they use the brakes to steer the aircraft during touchdown and rollout and for taxi operations to the parking ramp. Maintenance personnel examined the space inside the airplane's tailcone stinger and found ice. The ice was removed and the airplane was subsequently returned to service. Cessna issued service letter (SL)560XL-53-05 to provide a drain path for moisture that accumulates within the tailcone stinger. SL560XL-53-05 applied to 560XL airplanes with serial numbers between 560-5002 and 560-5544. Airplanes with serial numbers higher than 560-5544 had their SL560XL-53-05 drain hole incorporated in the tailcone stinger during factory production. According to the operator, this incident airplane, N498AB, serial number 560-5116, stinger’s tailcone assembly, part number 6612119-60, had a drain hole incorporated in it. The operator confirmed that this incident airplane’s drain hole correctly complied with the hole dimension and location indicated in SL560XL-53-06. According to preliminary information, on December 1, 2010, a Cessna 560XL, N607QS, operated by NetJets Aviation, Inc., sustained no damage when the airplane’s rudder bound during landing at the Toledo Express Airport (TOL), near Toledo, Ohio. The two pilots and one passenger were not injured. Visual meteorological conditions prevailed. The flight was operating on an activated instrument flight rules flight plan. The non-scheduled domestic passenger flight was conducted under 14 CFR Part 135. The flight departed from the Monmouth Executive Airport (BLM), near Belmar, New Jersey, about 1159, and was destined for TOL. This incident investigation's report number is CEN11IA087. An examination of N607QS revealed that ice that had accumulated in its tailcone stinger interfered with the rudder control cables and pulleys inside the tailcone stinger, which rendered the rudder immovable. However, a Federal Aviation Administration (FAA) inspector examined the airplane and found that the size of its tailcone stinger drain hole was smaller than the 0.201-inch hole indicated in SL560XL-53-05. The FAA inspector was asked to examine other Cessna 560XL airplanes’ drain holes that were present in the maintenance hangar that housed N607QS in TOL. Three other Cessna 560XLs drain holes were smaller than the 0.201 inch hole indicated in SL560XL-53-05. The other airplane serial numbers were 560-5305, 560-5548, and 560-5661. The serial number 560-5548 and 560-5661 airplanes should have had correct sized 0.201-inch drain hole incorporated in their tailcone stingers during factory production. According to notification information supplied to the NTSB, on December 20, 2010, a Cessna 560XL, N626QS, sustained no damage when this airplane’s rudder also bound during landing at the Idaho Falls Regional Airport (IDA), near Idaho Falls, Idaho. Cessna issued alert service letter (ASL)560XL-53-08 on January 21, 2011. The ASL, in part, stated: REASON The stinger may not drain water which may allow ice to form around the rudder bias cable pulleys. DESCRIPTION This alert service letter provides instructions to inspect for drain holes in frames immediately forward and aft of access panel 321ABC, and drill them if necessary. Instructions are also provided to seal an existing drain hole in the tailcone stinger and add a drain hole in the aft canted bulkhead. COMPLIANCE MANDATORY. This alert service letter must be accomplished within 90 flight hours or 90 days from the date of receipt, whichever occurs first. On March 15, 2011, the NTSB issued Safety Recommendation A-11-16 to the FAA. A-11-16 recommended that the FAA issue an airworthiness directive to require that all Cessna 560XL operators comply with Cessna ASL560XL-53-08. According to preliminary information supplied to the NTSB, on March 10, 2011, while climbing through approximately 28,000 feet in the vicinity of Haynesville, Maryland, a Cessna 560XL, N588QS, operated by NetJets Aviation, Inc., experienced stuck rudder controls. N588QS was modified to comply with ASL560XL-53-08. This incident investigation's report number is ERA11IA184. Cessna subsequently issued service bulletin (SB)560XL-53-16 titled Fuselage – Stringer Drain Installation on October 4, 2011. SB560XL-53-16, in part, stated: EFFECTIVITY MODEL SERIAL NUMBERS 560XL (Citation Excel) -5002 thru -5372 560XL (Citation XLS) -5501 thru -5830 560XL (Citation XLS+) -6002 thru -6080, -6082 thru -6086 The equivalent of this service bulletin has been incorporated on production airplanes -6081 and -6087 and On. NOTE: For airplanes affected by ASL560XL-53-08, Fuselage - Aft Canted Bulkhead Drain Installation, that alert service letter must be complied prior to or in conjunction with this service bulletin. REASON To install a seal and drain to improve water drainage from the stinger. DESCRIPTION This service bulletin provides parts and instructions to install a drain and seal that will reduce the amount of water entering the stinger and improve drainage. SB560XL-53-16 listed a drain tube assembly as part of its required materials. The FAA’s Wichita Aircraft Certification Office (ACO) approved Cessna's issuance of ASL560XL-53-08 and SB560XL-53-16. On May 11 through May 19, 2011, the FAA's Wichita Manufacturing District Office (MIDO) and ACO conducted a district office audit to evaluate Cessna’s quality control data for compliance with FAA regulations. That audit did not detect any misdrilled tailcone stinger drain holes on production 560XL airplanes. Cessna subsequently instituted a specific inspection characteristic to verify the drain hole installation. A MIDO inspector conducted a follow-up inspection on August 16, 2011, verifying engineering requirements, planning changes for technicians to follow, and actual holes to include their dimensions. The inspector also verified the drain scupper installation on the first airplane in production to receive it. The drain scupper is listed in SB560XL-53-16 as a "tube weld assembly" with part number 6612060-1.
The manufacturer's inadequate initial design and inadequate subsequent modifications of the tailcone, which allowed moisture to collect and freeze around rudder cables during operations in subfreezing temperatures, resulting in a loss of rudder authority during landing.
Source: NTSB Aviation Accident Database
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