Page 11 - Volume 11 Number 10

Brakes –
OEM versus STC
by Dean Benedict, A&P, AI
All King Airs come out of the factory with probes) generate a core charge billback. The rotable
BFGoodrich® brakes, and most come with a multi-
disc brake assembly. The only exceptions were the F90s and the 100s (straight A and B models) with standard gear, which came with a single-disc brake assembly by BFGoodrich (BFG). The multi-disc brakes by BFG have excellent stopping capability, but they’re very expensive to maintain.
Internal Multi-Disc
The multi-disc brake assembly is considered an internal disc setup. The discs fit together; the wheel, with special cut-outs to accommodate the disc assembly, slides around the discs. Relining or overhauling these items is very labor-intensive. The usual practice is to purchase an exchange brake unit. Your core unit is then returned for evaluation and credit (hopefully) against the core value. But as we have seen over and over, in recent years, most cores (everything from brakes to fuel
pool has aged, and some of the components needed for overhaul are so scarce they must be replaced with new. As the cost to overhaul a unit has increased, the core charge values have skyrocketed.
These days you can buy an exchange widget in overhaul condition with a core value nearly equal to a brand-new widget. Then, upon evaluation, if your core widget is deemed BER (Beyond Economical Repair), you end up paying the exchange price plus the nearly new price for a used widget. Even if your core isn’t completely condemned, you can bet on a billback, and a hefty one at that. Core charge billbacks, once the exception, are now the norm. But I digress ...
External Single-Disc
When it comes to the BFG multi-disc brake assembly, their exchange units have always been exorbitantly
A diagram from the King Air 90 manual (left) shows the internal, multi-disc BF Goodrich brakes that come on most King Airs out of the factory. The King Air 90 wheel diagram (right) portrays how the brake is sandwiched between the two wheel halves.
OCTOBER 2017 KING AIR MAGAZINE • 9
MAINTENANCE TIP