PURPOSE: (Verbatim from AC 23-27) "This AC provides guidance for substantiating parts or materials substitutions
to maintain the safety of old or out-of-production GA aircraft, or other GA
aircraft where the parts or materials are either difficult or impossible to
obtain. This AC also provides guidance about the data required to gain FAA
approval for making these substitutions. In this AC, "we" refers to the FAA, and
"you" refers to the aircraft owner or operator. You may use the data in this AC
as "approved" data for substantiating parts or materials substitutions to
vintage aircraft. The appendices include examples of parts substitutions and
guidance on recording minor alterations through logbook entries. These
guidelines will help owners avoid having to obtain a field approval for like
substitutions on subsequent aircraft."
The AC23-27 on Page 12, further states : "BEARINGS.
Bearing catalogs from general bearing supply houses state in their introductions
that the bearings listed in their catalog meet ANSI (American National Standards
Institute) specifications or exclusions. They also give cross-references.
Usually, they list bearings for aviation applications. You must use the
appropriate part from the cross-reference matrix.
Approval: This is a minor alteration and you may document it by a logbook entry.
The logbook entry must reference the manufacturer's identification and industry
specification for the original and replacement bearing."
CSOBeech is now able to offer the hard to find
original HEIM brand rod ends at attractive pricing which will support the
management and maintenance of the site. Please consider purchasing here to
support the CSOBeech.com site.
HEIM HM4, HMX5, HM5, HML6, HMXL6 and HM6 rod ends have
been found to be the Beech factory choice in their Part Catalogs as new parts on
the older vintage Baron,
Bonanza and Travel Air aircraft. Don't be a gear collapse statistic as a result
of a 50 year old fatigued rod end.
The HMX5 is used in the heavier later
model nose gear rod application. Two are usually required in the nose gear linkage.
The HMX5 has a thread pitch of 3/8"-24 and a rod end bore of 5/16". Check out this landing gear system narrative HERE for additional rod end info.
The HMX5 has no grease fitting but has a maximum static
radial load rating of 8,410# vs 4,920# for the same Heim rod end with a
lubrication fitting (HMX5FG). To verify this data, please see the HEIM catalog
As of 10/02/2018, HEIM had
very little stock on HMX5 rod ends and I may have purchased the last of them
until they schedule another run. I have limited availability of the HMX5 rod
end. So, here is
SealMaster Rod End
bearing catalog that you can compare specs to the HEIM
specs. You might look at ARE-5-20 on Page J-15. Also, HEIM lists the SealMaster
ARE-5-20 as an interchange for their HMX5 in this
Interchange Guide. Look
at Page 4 of the
Interchange Guide for the reference. If you and
your mechanic decide that the SealMaster ARE-5-20 rod end is suitable for
airworthiness in your aircraft, you can order that PN from me below.
The smaller HM5 is typically used in early Bonanza,
Travel Air and Baron nose gear rod ends at the nose gear well end of the rod
and at the "V"-Brace" arm to push/pull on the nose gear mechanism (#48 in the
part catalog extract below). The HM5 has a thread pitch of 5/16"-24 and a rod
end bearing bore of 5/16". The HM5 has no grease fitting in the shaft to lower
the load rating of the rod end. A little Corrosion X or ACF50 each year at annual
should do just fine like the original non-grease fitting rod ends did. Two would be required in the nose gear mechanism.
The HML6 is typically used on the nose gear rod that
connects to the landing gear transmission arm.
The HML6 has no grease fitting in the shaft to lower the load rating of the rod
end. The HML6 has a thread pitch of 3/8"-24 and a rod end bore of 3/8".
Measuring the threaded rod through the belly inspection panel is a GREAT way to
determine if you have the 3/8" shaft HML6 or the larger (7/16") HMXL6. A little Corrosion X or ACF50 each year at annual should do just fine like
the original non-grease fitting rod ends did. This is a LEFT HANDED REVERSE THREAD rod end
which makes the rod act like a turnbuckle to adjust nose gear tension values.
The HMXL6 is typically used on later model
Bonanzas and Barons. The HMXL6 is a LEFT HAND REVERSE THREAD large thread pitch
of 7/16"-20 with a 3/8" bearing bore that connects the nose gear rod to the landing gear transmission arm.
If you find you have HMX5 rod ends in your forward nose gear rod, you MIGHT
have the HMXL6 rod end at the back transmission arm connection.
The HMXL6 has a thread pitch of 7/16"-20 and a
rod end bore of 3/8". Measuring the threaded rod through the belly
inspection panel is a GREAT
way to determine if you have the 7/16" shaft HMXL6 or the smaller (3/8")
The HMXL6 has no grease fitting in the shaft to lower the load rating of the rod
end. A little Corrosion X or ACF50 each year at annual should do just fine like
the original non-grease fitting rod ends did. This left hand reverse thread rod end
allows the push rod to act like a turnbuckle to adjust nose gear tension values.
SPECIAL NOTE: As of March 2018, I
was advised by the HEIM/RBC factory that the HMXL6 is obsolete and is no longer
available! If your gear requires this particularly beefy rod end you will see in
HEIM Interchange Catalog
that the equivalent to HMXL6 is the Spherco AREL-6-20.
See the Spherco/Seal Master Rod End Catalog
HERE for specs and
details on the AREL-6-20. If you would like to buy this AREL-6-20 rod end,
scroll below and click on the Buy It Now button.
The HM6 is typically used on the Main Landing Gear
"push-pull" rods on the outboard ends (total of 2 per aircraft) as well as the
elevator push/pull rods (total of 4 per aircraft) on the Baron aircraft. The HM6
has no grease fitting in the shaft to lower the load rating of the rod end. The
HM6 has a thread pitch of 3/8"-24 and a rod end bearing bore of 3/8". A
little CorrosionX or ACF50 each year at annual should do just fine like the
original non-grease fitting rod ends listed in the Beech Parts Catalogs did.
The HEIM HM4 is typically used on the inner gear
door rods. The HM4 has a thread pitch of 1/4"-28 and a rod end bore of 1/4". A pair of HM4 rod ends is on
each inner gear door rod. A pair of HM4 is used on the nose steering rod in the
nose gear well and 4 HM4s are used on each outer gear door. Things to remember:
At the outboard inner gear door connection the
bolt head faces AFT!
At the inboard rod connection there are two
little bushings that can easily be lost (creating a mega PITA search or high
factory cost to replace). Cupping ones hand under the bolt during disassembly to
catch the bushings can avoid this potential headache.
Inner Gear Door Rods Painted and Corrosion X inside center of rod & fitted with
HEIM HM4 Rod Ends
Above are inner gear door rod ends all
cleaned up and fitted with four new HEIM HM4 rod ends. These rod ends take a lot
of pull tension since they are hard rod connected to the gear transmission.
Laying the rods out on a large piece of paper and marking the center point of each
rod end is a great way of getting the length close to the removed
length. Why leave 50 year old rod ends in that area of gear?
The HEIM HML4 is a LEFT HAND THREAD and is typically
found on the ailerons. The HML4 is no longer available. The HEIM Interchange Catalog
lists the SealMaster TREL-4 as a suitable replacement. The HML4/TREL-4
has a thread pitch of 1/4"-28 and a rod end bore of 1/4".
Check your IPC to confirm that this rod end is specified for your
HEIM Spec Sheet
A Few Words About Bonanza Ruddervator Rod Ends
It's been reported that older Bonanza IPCs show the ruddervator rod end to be a HEIM MD46-15
HERE is an Aurora Interchange spec sheet on the HEIM MD46-15M rod end which shows the Aurora GMM-4M-675 to be interchangeable.