What do I need to know about replacing all of the pressure hoses on my Musketeer Super’s engine?
Search strings: hose replacement, replace my hoses, engine hoses, Teflon hose, 124J, brake hoses, fuel hoses
Technical Editor:
There is a prior posting that addresses this; please be sure to read it as well.
My recommendation is that you order your hoses from Ashley (male) at Precision Hose Technology, 800-331-5946. Their link is on the BAC website (http://www.aircrafthose.com/). There are also several hits for this question if you do a BAC search on word strings such as replace my hoses or hose replacement. You should order them made from 124J hose. The ‘124’ is modern Teflon hose with an unlimited shelf and service life (read the search hits on BAC for Teflon hose). The J means extruded firesleeving, which is both more effective and far more convenient (much less bulky). The 124J costs only about 10% more than standard hose; but PHT will give you the BAC member discount of about 45%; you get the best hoses for what is typically a lower cost than field-fabricated replacement hose. The hoses will come fully TSO-tagged (an FAA requirement), and properly pressure-tested.
If you just call Ashley, he can fill your order based on a Kit of the hoses that Beech says came on your plane. But on an older plane that may have experienced many small changes over the years, the very best approach is to remove and tag your hoses one-by-one, then box and mail them to PHT for copying. Make note on the tag what each is for, as you remove it. Also make note if either end should have a different angle on it. Hoses having an angle fitting on both ends have a requirement known as ‘clocking’, to correctly place the end fittings relative to one another. There are instructions on the PHT website for this. Almost all hoses have a straight fitting on at least one end, to make clocking a non-issue. And finally, make note on each hose’s label if you prefer that it be longer or shorter, and by how much. Sometimes having a hose made an inch longer enables you to eliminate chafing due to some accessory that was added or changed over the years.
If you wish, Ashley can give you a rough estimate first. Your fuel-injected plane does have a couple more hoses than the carbureted planes.
You probably have about 5 fuel lines on the engine; make sure that the line from the Servo to the Divider (runs up between cylinders 1 and 3) has firesleeving on it; some originals did not. You’ll have two large -6 fuel hoses, one medium -4 hose to the Divider, then two small -3 pressure hoses from the Divider to baffle and baffle to firewall.
You will have two extra large (-8) oil cooler hoses, from the rear of the engine to the cooler.
You will have one small (-3) oil pressure hose, from the accessory case to the firewall.
In addition to these, you may have a manifold pressure line and gauge vent line that run from the engine to the firewall. These are often made from 1/8″ primer line; but it is far better to replace them with small hoses.
On the cabin side of the firewall, you will have some small hoses that connect the bulkhead fittings for the above (oil and fuel pressure, etc.) to the back of the instrument cases. These small hoses are usually found to be leaking, and should always be replaced when the engine side gets replaced. You haven’t lived until hot oil starts spraying on your leg from a failed 40-year old oil pressure gauge hose. Note that your existing quote is highly unlikely to include these very important instrument hoses. No one ever thinks about them until they fail and cause injury or other hardship. Note that the instrument hoses inside the cabin do not require firesleeving. I still consider it worthwhile getting them made in the 124J, if it is available, as they will then be good for life. The firesleeving will reinforce the small hoses, protecting them from vibration and abrasion. The 124J can also be used for the size -6 wing-root fuel hoses,making them lifetime hoses.
Special note: If you order new cabin and main gear hoses for the brake system (and retract system), these should NOT be made from the 124J hose. They must be made from the conventional black-jacketed high-pressure hose, which can (and will be, at PHT) be pressure-tested to 3,000 PSI. In a panic stop a healthy pilot can put 2,000 PSI on the brakes; and the retract system applies 1,600 PSI on the ‘up’ side. The 124J will appear to work in these applications, but could fail under some extreme condition. The 124J is strong enough (many times over) for the lower pressure fuel and oil applications.
Again, the very best approach is to evaluate each of your hoses for ideal length. Then remove and tag each of them, and ship them to Ashley with your instructions regarding length or type of end fitting (if you want to have an end changed). Make sure you get all of the instrument hoses on the cabin side, along with the engine side.