Springs in the Air

Tailwheel springs may need safety wires


Reports several months ago of a tailwheel spring clip coming off of an Aeronca has lead to a spate of reports of similar problems on different makes of taildraggers. Many mechanics encourage operators to safety-wire the retention clips.

An amateur-built Thorpe T-18, for example, suffered substantial damage while landing on a rough runway surface. The aircraft had just been completed and had been test flown at an airport with a paved runway.

The two test pilots then flew back to the home airport, which had a rough landing surface, and the tailwheel bounced hard. The spring retention clip rotated and came off of one of the tiller springs. The pilot applied brakes, but the other tiller spring steered the aircraft off the runway.

The aircraft hit a rock and came to rest inverted in a small pond. The pilot said, you know you have a problem when you are upside down and under water. No one was seriously injured.

Installing safety wires on the retention clips would prevent the problem.

Beech 200 King Air
Defective Wing Attachment Bolt

During a scheduled inspection, the wing attachment bolts were removed and inspected in accordance with the proper procedures. The required test revealed a crack at the junction of the bolt head and shank. The defective bolt was installed in the right aft lower position and had originally been installed as part of a manufacturer-supplied kit.Part total time – 2,475 hours.

Cessna 172RG Cutlass
Broken Nosewheel Bolt

During an instructional flight that included touch and goes, another pilot informed the pilot that the nosewheel of the airplane had fallen off. The pilot made a safe emergency landing.Inspection revealed the nosewheel axle bolt had failed. The remains of the bolt stayed in the right side of the nosewheels fork assembly. The condition of the bolt suggested the part had cracked some time before the nosewheel failure.The crack may have become a fracture a few weeks earlier when the aircraft was landed hard. Inspection at that time did not reveal the flaw. Technicians suspect the fracture may not have been visible. The flight school operating the aircraft has adopted a policy that the bolt be replaced any time a nosewheel tire is replaced.

Cessna 206F Stationair
Improper Rudder Assembly

During an annual inspection, the technician noticed that the rudder struck the elevator when both were at about half their travel. Rudder travel appeared within normal limits, however further investigation revealed that a seaplane rudder, which has a longer chord, had been installed on the airplane. Although the presence of the seaplane rudder was known, the Cessna 206 service manual makes no mention of rigging differences between the standard rudder and the seaplane rudder. However, the type certificate data sheet showed that the seaplane rudder had to have a 4-degree reduction in its travel.Part total time – 1,665 hours.

Diamond DA-20-A1 Katana
Defective Fuel Cell

After removing the fuel cell to accommodate rigging of the rudder control, the technician noticed that the fuel cells internal baffle spot welds were cracking through to the outer skin.Fuel leaks had occurred in several spots and the fuel cell was repaired. There are no provisions for inspecting this area without removing the fuel cell, nor have any inspection requirements been set by the manufacturer.Part total time – 990 hours.

McCauley D3A32C88 propeller
Defective Operation

The pilot reported that the propeller had been sluggish for the past year. Finally it would not return to low pitch during an engine run-up.When the propeller was disassembled, the technician found water inside the hub. The actuating pins were severely corroded and were binding in the links. Also the propeller blade races were severely corroded. During an inspection, most of the internal propeller parts were rejected. The propeller had not been overhauled for several years.

Mitsubishi MU-2
In-Flight Loss of Crew Door

While climbing through 18,000 feet, the right crew door blew off the aircraft. The aircraft was pressurized at the time and there was no prior indication of an impending failure. The plane was landed safely.The door had been installed shortly before the incident under a Supplemental Type Certificate. The door was not recovered, however an inspection of the aircraft and others in the operators fleet revealed several potential causes of the problem.The door-latch microswitch can be closed without engaging the door-handle lock. The mechanical lock, which must be released prior to rotating the door handle, uses a Hi-Lock fastener that can be installed in two ways. One way of installing the fastener impedes the travel of the door-locking shaft. A new door shipped from the STC holder had the fastener installed opposite others in the operators fleet. There are no lubrication requirements in the STC kit for the door handle or the locking mechanism.Part total time – 22 hours.

Piper PA-28-161 Warrior
Defective Flight Control Bearing

During an annual inspection, technicians discovered the stabilator bearing was excessively worn.When hand pressure was applied to the outboard end of the stabilator, there was about 2 inches of free play. The bearing was replaced.The hand pressure test may be useful in detecting worn bearings or structural damage. Excessive pressure may cause damage, but light pressure that reveals any free play or oil-canning of the skin should be investigated and repaired prior to flight.

Piper PA-28-181 Archer
Carburetor Air Intake Defective

During a scheduled inspection, the carburetor air box bushing and grommet were found to be severely worn.The nylon bushing and the grommet were worn completely through, leading the technician to conclude the parts should be replaced every 50 to 100 hours.If the bushings or grommets fail, material can be ingested by the engine.Part total time – 86 hours.

Piper PA-34-200 Seneca
Nose Landing Gear Trunnion Cracks

During a scheduled inspection, technicians discovered cracks in the nose gear trunnion. The cracks were located at the trunnion pivot point attachments on each side. They were approximately -inch long and were adjacent to the brace weld area.Part total time – 8,800 hours.

Teledyne Continental TSIO-520
Scored Cylinder

The engine was installed on a Beech 58P Baron at the No. 2 position. While being inspected by borescope, the No. 2 cylinder was found to be severely scored.The scoring covered approximately 50 percent of the cylinder wall surface and was well beyond the piston pin wear area. Large amounts of aluminum shavings were found in the engine oil filter. AD 97-15-01 covers IO-520 cylinders that use the same clyinder coating process as this cylinder, but this cylinder was not covered by the requirements of the AD. The cylinder had been ordered from the manufacturer and installed only a short time before this discovery.Part total time – 20 hours.

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