Squawk Box

February 2015 Issue




Antennas

The following information is derived from the FAA's Service Difficulty Recports and Aviation Maintenance Alerts.

Beech Model C33 Debonair
Improper Mounting
This VHF comm antenna was squawked for fluttering. Inspection revealed antenna was installed with no supporting doubler. Upon removal, a 5.5-inch radial crack was discovered around the antenna base, with a crack in an adjacent stringer. Skin under antenna also corroded due to no sealant being applied to base during installation.
Part Total Time: Unknown

Beech Model 200 Super King Air
Incorrect Specification
Aircraft was equipped with GPS/comm antenna that was recalled by manufacturer. Installed new antenna, p/n CI2480-100. During flt, replacement antenna vibrated loud enough to be heard in cockpit. Antenna removed and subsequently installed in same location on two other Beech 200s with no vibration noticed. Spec sheet for CI2480-100 previously stated maximum 350 KTAS and FL550. Revised spec sheet states 210 KTAS max at and FL200. Clarification is being sought from manufacturer.
Part Total Time: 0.0 hours


Cessna 172S Skyhawk SP
Improper Factory Installation
The GPS lost signal during an RNAV (GPS) approach. Found antenna’s BNC connectors were not crimped onto extender cables installed by manufacturer and the antenna was not properly sealed around perimeter or on fasteners at original installation. This allowed water intrusion, causing corrosion and antenna failure.
Part Total Time: 4236.0 hours

Cessna Model 208B Grand Caravan
Internal ELT Antenna Failure
Antenna (p/n 110-773) broken internally. Its top portion, including the wire whip, easily can be lifted off the base. Visual inspection alone will not reveal this disconnect. Antenna is part of the ME406 ELT system. This is the fourth incident of this condition on various airplanes in the fleet, all of which had lower time and cycles on the antenna than this one.
Part Total Time: 1800.0 hours

Cirrus SR22
Antenna Mounting Failures
The two GPS antennas on this aircraft are held in position with double-sided tape. In 272 hours they have come loose three times. The antennas should have mod to permanently mount them to the airframe.
Part Total Time: 272.0 hours

Piaggio P.180 Avanti
Separated Radalt Antenna
Radar altimeter reported inoperative. Found antenna sensor gone from the base, leaving 0.25-inch hole through the coax connection. The flat antenna (p/n ADS430101AC) mounts to a curved fuselage without contour adaptation.
Part Total Time: 3985 hours