Fire and Ice

King Air heater disables de-ice system for turboprops empennage


The following information is derived from the FAAs Service Difficulty Reports and Aviation Maintenance Alerts.


The crew of a Beech E90 King Air experienced a loss of empennage flight controls, which resulted in total loss of aircraft control, and the airplane crashed into a building during an instrument approach. The six occupants sustained only minor injuries.

Investigators looking into the crash found the problem may have begun under the floor at a heater register forward of the lavatory.

Two inches from the heat ducting is a tubing that supplies pneumatic pressure to the deice boots on the empennage. The heater register was at fuselage station 277. The pneumatic tubing was collapsed from 9 inches forward of FS 277 to 11 inches aft of FS 277.

When the plastic heating ductwork was examined, it was clear that it was structurally unsound. Investigators then blew smoke through the ductwork and found leakage throughout the system.

Collapse of the pneumatic tubing would have rendered the empennage de-ice system inoperable, and the King Air had no warning system to alert the pilots to the failure. Weather at the time of the accident included moderate snow and freezing fog, so tailplane icing is a prime suspect, although official final results have not been released.

American Champion 8KCAB
Fuel Leak

The pilot reported a strong fuel odor in the cockpit.The technician discovered the left fuel tank internal baffle had separated where it was welded to the lower tank surface and the fuel tank was leaking from a crack adjacent to the baffle weld area.This was the fourth reported occurrence of this defect in the aircrafts maintenance records. The internal fuel tank baffle is welded in the tank directly under the center-mounting strap, which may impose excessive stress on the structure.Part total time – 390 hours.

Beech B-23 Musketeer
Propeller Spinner Anomaly

A technician ordered a new propeller spinner to replace one that was severely damaged.When the technician received the new propeller spinner from Raytheon, he discovered it had been manufactured incorrectly, leaving a strip of metal across the propeller blade opening. The new spinner was accompanied by all the required paper work attesting to its airworthiness.Part total time – 0 hours.

Beech F33A Bonanza
Defective Fuel Control

The owner reported observing fuel flow fluctuations.A technician noticed the mixture control was very stiff to operate. Since the assembly was covered by warranty, he removed and replaced the fuel control unit without further investigation.Part total time – 34 hours.

Beech F33A Bonanza
Defective Wing Flap Indicator

The aircraft owner reported a problem with the wing flaps.A technician discovered the wing flap position indicator was defective and ordered a new part from the manufacturer. After receiving and installing the new indicator, he conducted an operational test that revealed the new indicator was also defective. During a bench test, the technician found the new indicator had a high amperage draw, indicating an internal electrical short. Part total time – 0 hours.

Beech A-36 Bonanza
Alternator Defect

While changing an engine cylinder, a technician removed the alternator to gain access to the work area, then elected to perform a 500-hour alternator inspection even though there was still ample time remaining.The technician discovered that several stator windings displayed evidence of overheating. The submitter stated his facility has been performing the 500-hour inspection outlined by Continental SB 01-3 at 400 hours because of a high failure rate. The alternator was working fine before the inspection.The FAA Service Difficulty Program data base contains an additional eight reports of alternator failures. Of those eight reports, six gave the operational time at failure: 304, 191, 173, 143, 39 and 10 hours.Part time since previous inspection – 242 hours.

Beech 58P Baron
Loss of Manifold Pressure

The pilot reported a loss of manifold pressure during flight.A maintenance technician discovered the turbocharger center bearing was severely worn. The worn bearing caused the turbocharger turbine wheel to rub and generate metal, which ended up in the engine oil. Part total time – 49 hours.

Cessna 172S Skyhawk
Alternator Failure

The pilot reported the alternator failed and the circuit breaker opened.A technician discovered the alternator contactor in the master control electrical junction box was defective. During a test, the contactor indicated resistance as much as 150 ohms. When he lightly tapped the contactor case, the reading was reduced to approximately 0.6 ohms.Part total time – 117 hours.

Cessna A185F Skywagon
Fuel Line/Electrical Contact

During an annual inspection, a technician discovered the left forward doorpost map light switch was in close proximity to the main fuel supply lines.The fuel lines are routed down the forward doorpost. AD 2001-23-02 deals with this subject in Cessna 172 series aircraft. AD 2001-23-02 requires the installation of an insulator on the back of the switch to protect the electrical terminals from contacting the fuel lines.The submitter suggested that AD 2001-23-02 be made applicable to all Cessna single-engine aircraft that have a map light switch on the forward doorpost.

Cessna 337D Skymaster
Circuit Breaker Failure

During maintenance, a technician discovered the engine cowl flaps were inoperative.The technician discovered electrical power was not being supplied to the actuator motor because the cowl flap circuit breaker had failed internally. It did not pop but would not allow electrical power to pass. Part total time – 75 hours.

Grobe 120A
Aileron System Interference

While completing a scheduled inspection, a technician discovered interference in the aileron control system.The technician discovered the aileron control rod was rubbing against the aileron bellcrank. To prevent further interference, he replaced the control rod and shimmed the assembly in accordance with the manufacturers technical data.Part total time – 98 hours.

Piper PA-28-181 Archer
Flight Control Cable Defect

During a scheduled inspection, an inspector discovered both forward stabilator control cables were severely worn. Also, the left aileron balance cable was excessively worn.The damage was adjacent to pulleys and fairleads where the cables are required to change direction. The submitter stated, The cable damage was caused by substandard cable and improper cable alignment by the manufacturer.Part total time – 2,592 hours.

Piper PA-28R-201T Turbo Arrow
Turbocharger AD

During an annual inspection, a technician attempted to verify the turbocharger housing part number to determine the applicability of AD 82-27-03.The technician removed the unit to find the part number and found it was not included in the applicability statement of the AD. Nonetheless, he inspected the housing in accordance with the AD and discovered the turbocharger housing was cracked.

Piper PA-28R-201 Arrow
Nose Landing Gear Defect

The pilot reported hearing a loud bang when he retracted the landing gear after takeoff. A few seconds later, the nose gear down-and-locked light illuminated. He extended the gear and made a safe landing.A technician discovered the nose gear clevis bolt, which attached the nose gear actuator to the down-lock assembly, was missing. The nose gear down-lock assembly was partially damaged when the bolt separated; however, it held up during the landing sequence.Part total time – 820 hours.

Piper PA-28RT-201 Arrow IV
Nose Landing Gear Defect

While conducting an annual inspection, the inspector discovered the nose landing gear strut housing was broken where the lower drag link attaches. Approximately half of the boss was missing. The remaining assembly was covered with grease, dirt and other debris. This discrepancy was only found after the technician cleaned the excessive grease from the assembly. He could not determine how long the part had been broken.The damage may have been caused by hard landings or misrigging the retraction system.Part total time – 5,554 hours.

Piper PA-34-200 Seneca
Wing Flap Failure

During a landing approach, the student pilot applied the last notch of wing flaps and the aircraft began an uncommanded roll to the right even when the pilot applied full left aileron. The flaps would not retract.The instructor observed the right flap had separated from the two outboard hinge points and folded upward and aft to a vertical trailing position. By reducing power on the left engine, he regained aircraft control at approximately 300 feet agl. A technician found the wing flap was severely corroded internally at the interfaces of the aluminum nose ribs and the steel flap hinge brackets. Evidence indicated the flap had been opened for maintenance prior to this incident and evidence of corrosion was apparent on the outside of the flap as well.

Piper PA-44-180 Seminole
Engine Air Intake Damage

During a scheduled inspection, a technician discovered that both engine carburetor heat airboxes were damaged.The right engine carburetor heat airbox was cracked at the hot air inlet where the tube is welded to the airbox. The crack was adjacent to the weld and traveled approximately half way around the tube circumference. The left engine airbox was cracked at the cold air inlet. The crack extended almost all the way around the tube circumference. The technician blamed poor airbox design and/or deficient welds for the condition. He said he had found several other similar failures involving like aircraft in his fleet. Part total time – 324 hours left and 199 hours right.

Piper PA-46-310P Malibu
Deice System Inoperative

The aircrafts deice boots were reported inoperative.A technician found the deice system manifold valve was broken. He did not give a cause for the break.Part total time – 3,975 hours.

Zenair CH-2000
Pitot Static System Defect

During a scheduled inspection, a technician discovered the line connected to the pitot static system mast was loose. He was able to remove the line nut from the fitting with his fingers. This installation uses plastic ferrules in combination with a brass nut. He speculated that exposure to the heat generated by the pitot static system caused the ferrules to shrink.


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