Selecting the Right Scheduled Maintenance Kits for Your King Air

The Beechcraft King Air soldiers on as the most popular turboprop aircraft of all time, with almost 7,500 total units produced over the two distinct product lines. They have proven to be highly reliable and one of the world's most durable and versatile aircraft. It remains the most popular charter aircraft due to its low cost of ownership and low maintenance costs. The King Air can also operate out of runways that other charter aircraft simply cannot do, whether due to length (or lack of it) or the airport's lack of support. 

But King Airs aren’t made of magic; they will break just like anything else. Keeping them properly serviced is critical to their long-term viability. We at Greenwood Aerospace are committed to keeping your King Air serviced with the highest quality parts and components, and one of the best ways to do that is with scheduled maintenance kits. Let’s take a look at how. 

King Air Aircraft Parts and Accessories: Landing Gear Inspection and Overhaul 

The landing gear is probably the most overlooked system on the aircraft, at least until it isn’t working. Then, it is at the forefront of everyone’s mind. The landing gear is a highly complex system that is tasked with the tall order of ensuring the safe transition from takeoff to flying and then absorbing the intense shock of transitioning back from flight to ground movement. Plus, it has to deal with the lateral forces of ground movement. It is a really tough job, and it takes tough, robust components to perform consistently, year after year, without fail. 

To make sure that your King Air is riding on safe legs, all King Airs are required to undergo an inspection cycle that is due at either six years or 8,000 cycles, whichever happens first. It is important to understand that this is an inspection cycle, not an overhaul. However, inspection cycles do not mean that items will not require repair. It just means that the primary purpose is not to overhaul but is instead to inspect the entire system. Now, inspection cycles are a good opportunity to conduct the applicable airworthiness directives if any need to be done. Mind you, this does not include emergency ADs; those must be done right away. 

Right and Left Engine Flammable Fluid Hose Replacement

All liquid-carrying hoses in the King Air engine compartment must be replaced in 5-year increments. This is for safety-of-flight because when a flammable hose comes apart, especially for a pressurized system, you basically have a firehouse of flammable fluids spraying over a hot engine and engine compartment.

Whether or not the flammable fluid hoses show significant wear, they are getting replaced. This is one of the best opportunities for a kitting service. A specific set of flammable hoses must be replaced with Beechcraft Corp.-supplied hoses only. In all, 15 hoses per side need to be replaced, so kitting these makes a lot of sense.  

This is particularly important because there are any number of inferior-grade aftermarket hoses that look identical to the OEM hoses, Only the OEM hoses are specified in ATA 05 because they are the only ones made to exact tolerances for the aircraft. Buy the OEM hoses as a kit makes great logistical sense 

King Air Phase Inspections

King Air's maintenance requirements include phase inspections. The aircraft conducted four phases of inspection, one of them in phases one, two, or four. King Air phase inspection usually occurs once every two years, and King Air Phases must complete each 24-month inspection program. Most operators prefer combining inspection phases for more efficient utilization of downtime in the field. Usually, it can occur if a flight of more than 400 hours takes place. An aircraft is usually subject to one of two examinations during Phase inspections or combining Phase inspections.

There are four different phase inspections, which are Phase 1-4, each conducted at 200-hour increments. There is no reason that you cannot combine phase inspections, so generally, the phase inspections are combined to reduce overall downtime. There is a certain level of overlap between the inspection work cards, and each phase adds a little detail or touches a system that doesn’t require as frequent of inspection.

King Air Engine Hot Sections

Another significant portion of the King Air maintenance process is Hot Section Inspections (HSIs). There are two separate sections in each PT6A engine: a hot section and a cold section. The components that comprise the engine's hot section are inspected during the engine hot section.

HSIs are conducted every 2,000 hours for some engines, although the entire list for every PT6A model is here and is a fairly simple ordeal. They can be conducted with the engine on the aircraft and are an intermittent inspection to ensure the hot section isn’t hiding any cracks or other hazardous potential failure points. 

All four phases must be completed within a 24-month window, and then the clock resets at that 24-month point. 

Engine Minor Inspection

Every 400 hours, an engine minor inspection is required. It is often performed along with a phase inspection to save on downtime, which reduces the overall cost. This examination consists of:

• Filter replacement for the fuel pump outlet
• The fuel pump intake screen is examined and cleaned.
• Drain cleaning for the P3 filter
• Examination of the engine control linkages
• Examine the secondary screen and the oil filter element

Five-Year Wing Bolt Inspections

A King Air wing bolt inspection is necessary every five years. This contains the Inconel wing bolts and nuts, which are visible and fluorescent liquid penetrant. It also has the left and right outboard wing lower forward main spar fittings and a magnified visual and eddy current. At the upper, upper, and lower aft wing attach sites, eddy current is also utilized to evaluate flat surfaces, depressions, counterbores, and bolt bores. 

This is another example where, if you are concerned about the bolt condition and would rather just replace them, assembling kits for your fleet of aircraft is a wise move. 

When you make a custom hardware kit for your aircraft or fleet of aircraft, you can be as elaborate as you would like with replacements, combining other complementary parts that may need to be replaced on comparable cycles. 

Parting Thoughts

This is far from a comprehensive list of the maintenance process for the King Air. Each model has different requirements, and even different models of the same engine (the PT6A) have the same inspections and repairs but on different cycles. You need to understand what aircraft you have, the inspection cycles, and why you need those inspections, repairs, or overhauls. 

When you know those things, you should contact our team to assemble parts kits for all of your maintenance requirements. Whether a simple scheduled maintenance kit of common hardware, seals, or an elaborate overhaul kit, we are here to help.