Landing Gear Rod Ends (Why You Need to Change Them)
Don't be a Gear Collapse
(LGRM*) Statistic!
This Rod End (and several others) is all that is between you and the above kind
of event!
The rod end pictured above is the factory
installed, 4,000hrs TT HML-6 Heim unit from the back end of the nose gear rod at
the gearbox on my B55. It looks perfectly OK doesn't it? But hey, who knows what the metal
fatigue cycling has done over 43 years. This CSOB does not want to find out!
Don't wait to have a Rod End failure to learn
that the insurance companies have been totaling older Beechcraft that have
suffered a landing gear rod end failure or gear up landing.
The above video looks to me to be possibly a Colemill Foxstar Baron with the nice winglets. Unfortunately, it's possible that
this plane's rod ends (in particular the nose rod ends) were left in there too
long, notice the floppy nose wheel on landing rollout.
Here is a Travel Air with a gear issue
executing a gear partially extended landing:
Many gear collapses are a result of rod end
failure (unfortunately, some are the result of confused pilots grabbing the gear
handle instead of the flap handle DUH! Fuhgeddabout touching anything until
you're clear of the active AND STOPPED.
Right behind your engine, the landing gear is
the next system, where a failure will cause major damage to your plane and/or
potential injury to you and/or your passengers.
The rod end pictured above is the factory
installed, 4,000hrs TT HML-6 Heim unit from the back end of the nose gear rod at
the gearbox on my B55. It looks OK doesn't it? But hey, who knows what the metal
fatigue cycling has done over 43 years. This CSOB does not want to find out!
It has been reported that the HMX5FG has been
superseded by ADNE5-323 for the two front rod ends and the aft rod end is
ADNEL6-317.
True CSOBs hate to have expensive things break
or fail.
So spend a little dough to avoid a potentially giant headache and the loss
of your plane. Visit your mechanic and have your rod ends changed at (pick a
number you like: 2,000hrs TIS, 3,000hrs TIS, 4,000hrs TIS).
Click
HERE
to see what happens to a 7,000 TT Rod End and see how the tensioning spring is nearly
"Stacked"! This owner was incredibly lucky in that when the middle
nose gear rod end
broke the nose gear came down but had ZERO downlock tension.
Here is a quote from A-33 Bonanza
owner of the above failed rod end, Stan "The Man" says:
"You must replace these rod ends at no more than 3,000 hours,
you are gambling on a failure that may result in a landing with the nose gear
not extended! I was very fortunate, the aft nose gear retraction rod pushed the
front nose gear retraction rod to lower the gear with the failed rod end. I felt
a thump when I retracted the gear and didn't know what the problem was, so I
extended the gear for the next landing, at home base, at under 100 knots and did
a gentle, smooth landing and slow taxi to the hangar on smooth pavement. When we
retracted the gear the next day on jacks, the nose gear did not retract. We were
very lucky not to have landed the Deb with the nose gear not extended or in
having it fail on the ground. Please do not neglect the nose gear retract rod
ends, there are three of them."
Here is a great low cost source of genuine Heim
Rod Ends: Bearing Chain
& Supply in the great state of Texas
FAA-PMA replacement rod end bearing for Beechcraft p/n's:
131553-4M, HM4, HM4M, HM4U. Eligibility includes Bonanzas and
Barons.
SSV35-231553L4M Rod End
List Price: $31.50
FAA-PMA replacement rod bearing for Beechcraft p/n's:
131553L4M, HML4, & HML4M. Common installations on Bonanzas &
Barons
SSV35-231765-3M Rod End
List Price: $29.80
FAA-PMA replacement rod end bearing for Beechcraft p/n's:
131765-3M, MD46-15, & MD46-15M. Common installation on
Bonanzas & Barons.
SSV35-231765-1F Rod End
List Price: $17.58
FAA-PMA replacement for Beech p/n's: 131765-1F, F34-14,
F34-14M, REB3N. Eligibility includes Bonanzas & Barons.
While you are changing the rod
ends get yourself the tensioning springs as well! There is one on the nose gear
rod (pictured above) P/N 35-825188 and one on each main gear push-pull tube that
are P/N 45-815091 for the B55.
RAPID has
these springs and new tensioning washers. My main gear springs were P/N
45-815091 and the washers are P/N 100951S063XP. Check YOUR parts catalog
to be sure you order the proper P/N for your model and serial number!
Here's a Beech Lister's method for compressing the nose gear spring:
Other methods include a vice to squeeze the ends and careful removal of the
shear pin. Be sure to lube the shaft liberally with CorrosionX or ACF50 or some
such lube before reassembly.
Another suggested method from Bo
owner Bill:
I clamped a long piece of metal in the vice, clamped some C clamps
strategically to it to act as a stop for one end of the rod, and then used a
furniture clamp to squeeze the overall rod enough to remove the pin that holds
it together. Worked great, and didn't send parts bouncing around the shop when
it slipped out of the vice.
Bill also reports that Arrell
Aircraft sells a cleaned up re-tempered spring for less than half the Beech
Factory price. So if that spring price bugs you give Arrell a call at the info
on this PAGE.
ALSO: Don't forget to put new nut
and bolt hardware into your landing gear. For example part # 48 (Beechcraft P/N
available only from
RAPID or
Arrell Aircraft) in
the below parts catalog extract. Your parts catalog will list all the AN or MS
hardware for each rod end connection.
A great CSOB hardware source is
Haire
Aviation. See my page on Haire Aviation
HERE . Just call them
up and give them your list.
Here are the two versions of Nose
Gear Arms that are used at the landing gear transmission to actuate the nose
gear. Note the top "beefy" one is used on Barons and possibly later model
Bonanzas.
Picture Courtesy of Kevin O.
Per Kevin: Beech has gone through 3 generations of these
arms--the first couple of years the part number was 35-825172, it was made of
magnesium.
Beech had a AD , or maybe a SB to change it out to an aluminum
one ( part # 35-825172-2)--they used this part till the 80s--thats when they
switched over to the beefier one 35-825172-13
All Baron 58s used the 35-825172-13 until 1984. The Model 55 Barons got the
-13 with the 1974 model. Current p/n is 104-820050-3 for all replacements.
Below is perhaps part of the reason that Beech went to a
beefier arm. All of the early Bonanzas and T34s are reported to have had the thinner arm depicted
below.
Below is the nose gear retract arm and bolt. Notice the bolt has the slotted
head facing the pavement. The castlelated nut is torqued using some thin washers
to get the proper hole placement for the cotter pin. Yeah, it's a PITA to
do.....
While you are in the Main Landing
Gear area spiffing everything up like new, check out the main landing gear
sleeves info HERE
to put the finishing touches on your rod end and landing gear refurbishment.
Also, the nose gear retract rod
boot cover is PN: 35-825076-13 @ $47.74 on 02/02/2009. A bit steep IMHO for a
little fabric cover that fits over this area:
Here is another JUST IN THE NICK
OF TIME save by Paul S. on his N35 Bonanza. The below pic is of the shear pin in
the nose gear rod assembly (see pic above) of his N35. Just goes to show you that it's a good
idea to disassemble and look at these components that have been in service for
so many years:
Paul being the avid Beech Lister
that he is, has been listening to all the posts on the Beech
List about high time landing gear
parts and in his annual on his 5,000 hr TT airframe got his rod end project
going with his IA. The picture above is of the pin that maintains the two pieces
of nose gear pushrod together against the tension of the spring. This would be a
really good time to inspect the braze and inner rod section.
Per Paul, in the down position
this pin floats in the slot of rod #50 in the below picture and your spring
(part #51 in the below diagram) provides the downlock tension pressure. In the
up position, this pin takes the brunt of your UPLOCK TENSION. It would stand to
reason that is this pin is mangled (or worst case, shears, then the uplock
tension adjustment was probably massive), just a hypothesis mind you.
Here is what this problem might
look like in the air
:
The latest info from Beechcraft
parts guru Kevin O. is that this shear pin used to be Beech PN: 45-824014 BUT it's no
longer available. Kevin reports later model parts books call out AN394-25
or a MS20392-2C25, available at Aircraft Spruce for about $0.30. Kevin suggests
changing this pin about every 1,000 hours and lube and inspect the inner shaft.
On early model Bonanzas rod #50
had a short nose, so when your pin sheared, you had a very bad day. Beech
engineering got wise to this flaw and made later model Bonanza/Baron shafts
longer, so when the pin sheared, your nose gear stayed down AND the shafts
stayed together, so on your recycle of the gear you were down and locked again.
Great save by Paul in finding his
nearly sheared pin!
The pin is #52 in the below
Diagram:
Here is another near-miss shear
pin find by A36 owner and Beech Talker Mike S.
Check out this vintage Beechcraft
Service Bulletin HERE
issued in February 1957 when they changed to a longer plunger rod and a shear
pin that replaced a shorter plunger rod and a clevis pin.
The newly specified shear pin at
that time was PN: 45-824014
The newly specified longer
plunger at that time was PN: 35-825094-4
Back then they called it Kit #
35-619
Here is another near miss catch
by Beech Lister Jim H. on his 1955 F-35 Bonanza. During the process of changing
out his nose gear rod ends, he found the gear door actuator pin almost severed
in half!
Here is Jim's pic of the before
and after a welding repair. Jim reports 5,400TT hrs on his Bonanza. A near miss
of his nose gear door actuation averted!
Nice save Jim!
This is the slotted tab that the pin goes into to actuate the
nose gear doors.
OK, so you need to see more
"shock & awe" pics of what's lurking in that airframe-saving system we call the
landing gear before you make the commitment to check yours out?
Well here you go, courtesy of
BeechTalker Ron H. His BeechTalk thread is
HERE. His synapses and pics of his nose gear retract rod shaft are below:
In taking the recommendations of the ABS and others about
replacing the nose gear rod-end bearings, I took these to heart and did mine
during the annual inspection on my bird which is just wrapping up. All of the
nose gear rod-end bearings, bushings, and hardware have now been replaced.
We found an anomaly in the rod assembly, fwd nose gear retract link as shown in
the attached pictures. What caused it, I have no idea, but can only surmise that
the previous owner who was learning to fly in the plane must have had a nose
wheel first hard landing. Again, I just don't know, and can only speculate as to
what might have caused the sleeve to split like this.
I also found one rod-end bearing that had a crack across the crown, and down one
side towards the bolt hole. I know that it would have eventually failed, but
when is the question.
Thanks to the ABS and the others preaching on the need to replace the rod-end
bearings, I found these two potential failure points before they did fail and
result in unpleasant results to our pride and joy as well as ourselves and/or
potentially others.
Here is what the damaged retract rod shaft looks
like with the spring on it. This is a good example of why these things should be
completely disassembled, inspected, lubed and put back together if all is well:
Note the damaged portion of the shaft that is
barely visible through the spring!
Paul S. adds the following comment: the inner shaft (forward section) extends far enough down the
tube so that if the pin shears, the nose wheel will hang in the wind, but the
rods will still interface enough to extend gear properly. This was changed with
s/n D-4547.
Great CSOB save Ron!
Here is another disaster waiting to happen to
older airframes. Check your drag link for any evidence of stress cracks or
casting anomalies:
Remember, a gear up or nose gear collapse will
likely total most anything but the latest of airframes. Between the prop strike
teardown/inspection and the sheet metal repair you're looking at quite an
expense. This was a bad day for this Bonanza owner!
Here is what happens when you don't check the
clearance of your doors before doing a full blast retraction test. Hey, it's on
jacks, so what I like to do is use the crank, turn it CLOCKWISE just enough turns to get the inner gear
doors to open up while you or your buddy checks the clearance to your jacks.
There should be very little resistance in turning the crank for the amount of
turns to open the inner gear doors. STOP when the inner gear doors open up or
the cranking resistance begins to get noticeably harder (this indicates you are
beginning to lift the main gear and you do not want to do this with the little
worm gear and crank).
Picture Courtesy of Kevin O.
Oh yeah, and the same thing can happen if you have
your inner gear doors disconnected and the rod hanging in the breeze. When you
go full blast with the gear motor the rod is going to go in and out of the side
of the plane - at full speed! Yup, you guessed it, it can get hung up in there and things are
going to get bent. Consider that 24V gear will cycle in about 4 seconds and 12V
gear in about 8 seconds. What I like to do is put a piece of tubing or rubber hose
over the rod end and make sure that it extends past the fuselage, and is really
secure.
This is the nose gear
door rod and actuator cam/pickup fork. That flat end on the left side of the cam must be
firmly planted on the "L" shaped piece that is on the left side (of
this picture view, right side of the aircraft fuselage) of the
inner wall when the gear is down and locked. If your gear door rods are ever
removed it is easy to reassemble them to the gear doors in such a way that the
cam/pickup fork is slightly turned counter clockwise and the flat part of the cam will not be flush with the "L"
piece on the wall of the well. You will then have nose gear doors that do not close properly. Don't ask
me how I know!
Here are pics of Beechcraft Maven,
Kevin O's. "owner produced parts" for the nose gear door actuation:
Per Kevin:
"The first picture shows
owner produced new cross shaft for my deb--also the end plugs and new
gussets--also pictured is a factory made pin that attaches to the lift legs.
Kevin O.
Thesecond
picture shows difference in gussets---the original is made out of aluminum--the
steel shaft rotates on it and it gets play--screws up the rigging on the gear
doors and the cowl flaps---the one I made has a bronze bushing installed---it
has over twice the surface area for the shaft to ride on---we had to make the
plug that goes in the end of the cross shaft (only found on debs without cowl
flaps and barons) 1/8 " longer to give room for the added thickness of the
bushing.
THIS is the way
the factory should have made them !"
Bad Landing Gear
Transmission Sector Gear
The above picture
is courtesy of Beech Lister and B55 owner Derek D:
Above is a fuzzy picture of one end of a bad gear with an even
fuzzier view of the red tag attached to it. It was deemed unserviceable because
of the tooth wear seen in the photo, particularly on teeth 2 through 6 (starting
end-right and counting left). I was told this probably occurred over time due to
a improperly adjusted dynamic relay.
These worn teeth, and similarly worn teeth on the other travel
end of the gear, were the only two spots highlighted in red marker as "bad". I
don't know if this was all that was wrong or if they stopped inspecting once
they found something egregious. I am also unable to tell if the wear in the rest
of the teeth going left is acceptable or not.
Thanks for the contribution Derek!
Here is a picture of the Beech
sector gear, courtesy of Travel Air owner Jeff W:
Jeff's comments:
If you see the shiny marks in the middle of the teeth, the ones that you can
see in the middle are normal, but at the end, maybe last 8-10 teeth on either
end, those marks deepen into a gouge that you can lay a razor blade across and
get a feeler gage under. I forget the limit of that depth, at the time i was
talking to Jeff at Aircraft Systems in Rockford, he coached me through sorting
the gears so that I could only send him ones that were likely candidates. My
gearbox was overrunning the stops, and judging by the junkyard gearboxes I was
getting, so were lots of others.
It is widely believed that
Boston Gear has
been the supplier of this part, but who really knows?
HERE is
a primer on gear design/theory.
Landing Gear Transmission
Secrets Revealed
Here are pictures of the
landing gear transmission box
Pretty simple mechanism huh? You can see
that the sector gear is the real business end of this thing.
Here is some transmission gear
lube info posted by A&P & Beech Owner Bob B. of Texas:
From Beechcraft Communique #102
June, 2003
"The motor gear box should be packed with grease conforming to
Mil-G-81322 = Mobilgrease 28 (Shell Grease 22) The landing gear actuator itself
should be filled with approximately 1/2 pint of 75 weight gear oil conforming to
Mil-PRF-2105 (supercedes Mil-L-2105)."
Initially, Mobil Compound GG was specified to meet this
requirement. *This* lubricant is no longer available and was replaced by a
synthetic lubricant. In addition to Mobil 636 another Mobil product
has also been approved by the factory for servicing landing gear actuators.
Mobil SHC ..........available through our spares system under our part number of
101-380016- 1 (5 gal)"
Note the GG was the lead product! Only Performance Aero seems
to have a smaller than 5 gal quantity that i know of. However there may be
another newer Communique. Any lube meeting the Mil Spec is adequate in my
opinion.
Another pirep states:
Beech specifies Mobil Delvac 75W-90 gear oil, "which meets
the same MIL-PRF-2105 specification as Mobilube SHC."
PLEASE NOTE: As with all things on CSOBeech,
be sure that YOU independently confirm all information with your A&P/IA before
relying on this posted information. Remember, you, the owner/operator are
responsible for the airworthiness of your aircraft.
Here is a gear box that took a
pounding. A hypothesis is that after the gear up landing, the operator placed
the switch in the down position. Like that was going to lift the plane off the
ground and allow the plane to be rolled off the runway
.
Wonder what shape that sector
gear is in?
Here is what NOT
to do when placing your repaired or overhauled landing gear motor back in
service - Don't pack it with so much grease that you get grease all inside the
armature. Pics and below narrative courtesy of Kevin O:
A guy called me a couple of weeks ago bitching about his second gear motor
going bad in 3 years--asked me to look at it--said OK when I received it and
opened it up--the first picture is what I found. In the shop manual it states to
use one ounce of grease in the area between the motor and the landing gear
trans--placed below the mid point.
Whoever was installing the motor was packing it full--over a few months the
grease would leak over into the motor--coating the brushes and armature and
windings--causing the loss of dynamic brake and making the gear retraction times
slow.
Picture below is of a gear motor with 2000 hours on it--the black stuff is
just carbon dust from the gear brushes (normal) To save you guys time and money
( and maybe the loss of plane and injury )--use the correct amount and type of
grease
Read the spec for
lubricating the gear motor before install
HERE
Comments from
Kevin O. regarding install of the gear motor
The space between the motor and
the trans should be LESS than half full ( more like 1/3--any more and it will
leak into the motor as seen above. Also make sure that there is a washer on the
reduction gear that inserts into the motor ( they tend to get lost and then the
gear starts eating into the housing of the motor ALSO---have the plane on
jacks---retract the gear 1/2 way up--remove old motor and replace with the new
motor---then with the gear switch in the up position---hit the master switch for
just a second--make sure the motor is connected in the correct way ( its
retracting)--then cycle the gear both up and down and make sure you have the
correct 1/8th to a 1/2 turn on the trans to get it to hit the stops.
Do NOT cycle the gear a bunch of
times without letting it sit for awhile and cool down--you do not want it to get
hot--can screw up the windings.
Here is a picture
of the Landing Gear Motor Drive Gear. That little gear drives the whole landing
gear system! Rumor has it this motor is a descendant of the motor that rotated
the gun turrets in WWII vintage bombers.
No longer a "rumor", this sure looks like the ancestor of
our flap motors on this B26 Martin gun turret!
Now what are the rest of you
Beechcraft owners with original landing gear components in your 3,000, 4,000,
5,000, and 6,000+ TT airframes waiting for!
Click
HERE
for More Landing
Gear Rod End Tips, Sources, Rod End Catalogs and Part Numbers
See the ABS Landing Gear
Inspection Manual HERE . It
is a great reference for doing a thorough gear inspection and setting the
rigging to the proper specs.
YOU'VE
GOT TO READ
THIS Landing Gear Tip: Is your mechanic taking the slack out of your inner gear door
mechanism by tightening the turnbuckle rods? Maybe there is a reason for that
slack in the mechanism?
Ask your mechanic to examine the play/wear of this
Bushing/Rod
End and
Bolt
combo that attaches to the top transmission swing arm before tightening up the
linkage. Part total time estimated at 4,000 hours. The bolt was worn down
0.005" and the rod end would not even hold the bushing anymore.
Here is my gear door arm showing a slop
"signature" on the transmission arm, found during my annual. This is going to be
fixed with new pieces.
This tip
and many other landing gear tips are compliments of a VERY EXPERIENCED Beech
Lister who found this slop and dug further when he was installing a freshly
overhauled gear motor in his Debonair.
*For more info on LGRMs (Landing Gear Related
Mishaps) visit:
Mastery Flight Training
created by Tom Turner, ABS' Executive Director
Landing Gear Rod Ends (Why You Need to Change Them)
:
