By General Aviation News Staff · August 11, 2022 · 3 Comments

This is an excerpt from a report made to the Aviation Safety Reporting System. The narrative is written by the pilot, rather than FAA or NTSB officials. To maintain anonymity, many details, such as aircraft model or airport, are often scrubbed from the reports.

Conditions were widespread IFR with 500 AGL ceilings and about 6,000 MSL tops.

The aircraft was equipped with one PFD, one HSI slaved to a computer and magnetometer (no battery backup), and the remaining standard gauges. Each instrument had its own independent battery backup.

The left seat pilot was the aircraft owner and a CFI. The right seat pilot was a CFI/CFI-IA/MEI. Both pilots were IFR current and proficient and had recently flown together in this aircraft under simulated and actual IFR without incident.

The right seat pilot also had an EFB device with an ADS-B (independent battery plus accelerometer) as a backup navigation source (was turned on and accuracy verified prior to takeoff) and a handheld NAV/COM radio.

The right seat pilot filed an IFR flight plan from A-B-C-A with airport D as an alternate. The departure and approaches to airports B and C were without incident. After executing the ATC-assigned missed approach at airport C and reestablishing contact with ATC, ATC requested that we disable the transponder altitude reporting capability as it was sending faulty altitude information that was incorrect by several thousand feet.

Several minutes later, all power to all the Nav/Com was lost. The right seat pilot assumed the controls as the pilot flying and continued to fly the aircraft using the functional PFD/AI and utilized his EFB device app for GPS position and course information.

The left seat pilot was able to temporarily reboot the Nav/Com and reported to ATC that we were experiencing intermittent electrical failures.

We again lost all Nav/Com power, including the GPS and HSI. We were initially unsuccessful in restoring power to the Nav/Com.

The left seat pilot disabled all unnecessary electronics and continued to troubleshoot, including reviewing the POH emergency procedures. He also noticed that the HSI circuit breaker had popped and reset it. He was able to restore power to the Nav/Com again for about 20-30 seconds, long enough to obtain an ATC clearance for the approach to Airport A.

The HSI had lost all input from the computer and the magnetometer since neither had a battery backup. The only sources of navigation remaining were the EFB device slaved to the ADS-B and the magnetic compass.

The NAV/COM radio could potentially have been used to fly the localizer once we were close enough to the airport, however we were unable to pick up ATC or localizer using the handheld at the time (no external antenna). Neither pilot was able to get a cell phone signal to call ATC/Tower.

The ceilings that had previously been reported (and currently reported via the ADS-B) for home airport A, the alternate, and in the surrounding airport were all about 500 AGL, which is just above the MDA for the LNAV for the approach at airport A for which we were previously cleared by ATC.

With no operable communication, the pilots continued to intercept the assigned final approach course and fly it using the EFB device providing position and course information, along with a georeferenced approach plate. The approach was completed without incident, transitioning to VMC above the minimum descent altitude (MDA).

Once on the ground, the pilots were able to communicate with Tower via the handheld radio that was reported as weak but readable.

It was later discovered that the wire providing power to the electrical/avionics bus had somehow shifted and was severely burned by the exhaust manifold.

Join 110,000 readers each month and get the latest news and entertainment from the world of general aviation direct to your inbox, daily. Sign up here.

On Cessna 172K the only real indication of failed alternator was radio readout going dim – then out completely. Ammeter worthless. Voltmeter as a minor alteration made life good again. A flashing LED low voltage indicator by Eric M. Jones powered from cigarette lighter made life … WONDERFUL!

“Somehow shifted” is poor securing of the wiring. An external antenna jack for the hand held could have overridden a fortune in useless avionics.

And it sounds like the batteries for the hand held needed charging or replaced if that radio was weak standing outside the aircraft and talking to the tower/ground.

Your email address will not be published. Required fields are marked *

Save my name, email, and website in this browser for the next time I comment.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

© 2022 Flyer Media, Inc. All rights reserved. Privacy Policy