CESSNA 421 / 421A / 421B / 421C
The pressurized, twin-engine, 6 place Cessna 421 was certified in May 1967. This aircraft had (2) 375 HP geared and turbocharged Continental engines. Maximum takeoff weight was 6800# and maximum landing weight was 6500#. Maximum fuel was 175 gallons.
The 6 – 7 seat C421A came along in November of 1968 also with (2) 375 HP Continentals. (All C421 models have 375HP engines. Some would argue that, though their POH indicates that the engines are 375 HP, their engines actually are rated higher than that).
The 6 – 8 place C421B was certified in April 1970. The fuselage length was increased. Gone were the cowl flaps and the cowling sprouted numerous openings for engine cooling. The C421B had a maximum of 7250# or beginning with s/n 421B0201 - 7450# takeoff weight, but only 7200# landing weight. Beginning with s/n 301, up to 10 seats could be installed in this aircraft.
In October 1975 the C421C was certified with up to 10 seats installed. Maximum fuel quantity was increased to 206 gallons usable and the tip tanks were gone. Later 421Cs incorporated trailing link landing gear.
The RAM 421C indicates a maximum takeoff weight increase of 110# over the stock C421C and a little better twin engine climb rate. There was no real magic to this; the increased takeoff weight came at the expense of longer takeoff roll. The climb rate would have decreased also but a higher climb manifold was recommended. The winglets give a better twin-engine and single-engine climb rate. How about 225 TAS at FL 200 at 70% power!
QUIRKS
Probably the weakest parts of the C 421 are the engines. They require gentle handling to make TBO. Classroom time will discuss ways to help the engines make TBO.
The next weakest part of the airplane is the landing gear system. Ensure that this system is looked over by someone very acquainted with the Twin Cessna landing gear.
I’ve noticed that the emergency gear extension system does not work on some aircraft I have conducted training in.
The next item is the fuel system. We will discuss the fuel system in detail in class. In the twin Cessna’s with tip tanks, they found that if you were low on fuel and in a fairly steep nose down attitude the fuel pump could not pick up that last ~ 5 gallons of fuel from the front of the tank. The solution was to put a transfer tube at the front of the tip tank- and have a constant running electric fuel pump draw fuel from that area and put it next to the fuel pump. The operation of these pumps should be checked during preflight – just turn the battery master switch on and go out and listen to these “ticker” pumps (located at the rear of each tank) operate. If no noise – no go. They are required to be operating to fly. There are numerous other items in the fuel system to be discussed during class time.
Another item that can be confusing is the nomenclature. This can also be discussed in class.
The C421C fuel system differs significantly from that of the C421, C421A & B models. This can be discussed in class.
Fuel selector – The fuel selectors can leak. Even if you have the fuel selector in the proper detent, fuel can drain from the tip tank to the aux tank if the aux tank is not full. (C421, 421A, 421B).
Exhaust – the exhaust system needs to be inspected for deterioration, cracks etc.
Wing spar – fortunately for now the wing spar AD does not apply to Cessna 421s. The purchaser of a C421C though, needs to be vigilant to see if the wing spar AD eventually will affect his aircraft.
After the initial full power climb to 1000’ AGL (or whenever power is reduced to cruise climb power setting), the airplane “falls on its ‘butt’” i.e., the climb rate decreases significantly.
Be cautious of engine cases & cylinders cracking. Be very gentle with power changes.
You may find that you need to burn more fuel during cruise than recommended by Cessna.
MY OPINION
A well maintained C421 is a very capable airplane. Although this aircraft is very capable, it is also capable of having significant and expensive maintenance issues. The geared engines have been problematic. Cracked cases, cracked cylinders, deterioration of the viscous damper with subsequent severe vibration of the engine, starter clutch failures etc are all known to occur. You never want to be in a position to have the propellers driving the engines unless you’re at very low power, such as on short final to a landing. You will find that AFTII is VERY cautious (slowly retarding the power) about simulating engine failures in these aircraft. Do be prepared for engine failures, both in engine-out procedures and financially. If looking to purchase a C421, or any airplane for that matter, have a pre-purchase inspection accomplished by one who really knows the Twin Cessna line. As with any airplane for sale, there are those that are cream puff and those that have been maintained just barely well enough to keep flying and those in between. I believe that regardless of the condition of the aircraft, you will still need to consider what the cost will be to bring the airplane up to your standards. Do you want engine monitors; do you want an upgraded autopilot, navigation systems with the WAAS upgrade..? No, these do not make the airplane fly faster but they sure can enhance situational awareness and help make the challenge of flying the aircraft into IMC and busy airports manageable and safe. But this is a discussion for another time.
OBSERVATION – The C421s are no longer being built.