September 2010


As the project with my MD500 continues, I am continually amazed at the complex nature of some seemingly very simple repairs and everything that has to go into the repair process for each repair.  This includes design of the repair, documentation of the repair itself and the exact procedures to be used for the repair, justification for the repair, margin of safety evaluations for the repair, references to design documents, structure catalogs and more. All of this has to be documented (in this case a full 15 pages of documentation, pictures, figures, evaluations, metal and alloy material statements) and then forwarded to the FAA DAR (Designated Airworthiness Representative) for approval BEFORE the repair can be done.

I glance at something and think to myself – that looks like a 5 minute repair job. A little bondo, a little paint and hey, we are back in business. As part of this process with my 500, the folks at PHI are teaching me a great deal about the process a repair has to go through from start to finish. I thought I would take this opportunity to share with you the process for just a single, simple repair.

Lets start with what I assumed would be a simple repair. In the MD500, there is a cooling fan and a shroud and ducting that sits behind the back passenger area. This shroud and ducting has a tendency in the 500 to rub on what is commonly referred to as the Station 124 Canted Beam. This beam is part of the main structure of the helicopter and hence is pretty important to the overall airworthiness of the aircraft.

Take a look at the pictures below. This is the “damage” caused by a little rubbing of a cooling duct over years and thousands of hours of service.

Station 124 Canted Beam Damage

Station 124 Canted Beam Damage

Station 124 Canted Beam Damage

Station 124 Canted Beam Damage

Now I don’t know about the rest of you, but a little scratch .008″ deep just does not set my alarm bells ringing…heck the neighbor’s cat did worse than that to my BWM the other day when it decided to run across its hood first thing in the morning! Thankfully, I am not the one that decides which repairs are important and which repairs can be corrected with a little 80 grit and some white rustoleum! This canted beam is integral to the structural integrity of the 500 and it required repair.

As I said earlier, PHI went to work putting together the necessary documentation showing how they intended to make the repair, proved via engineering calculations that the tensile strength of the repair would be the same or better than the total replacement of the canted beam and received FAA DAR authorization to complete the repair.

(Click on the sheet for a larger view)

Station 124 Canted Frame Illustration

Repair Report for Station 124

In the above document pages, you can see where PHI is using the MD documentation to show the exact location of the repair to be completed and just a small part of the planning information that went into the repair showing all of the documents they used for the engineering justification. Further we see an exact CAD drawing of what the repair will look like when it has been completed.

Figure 4 Showing Repair

As you can see from just a few pages of the 15 page repair report, there is a lot of information and engineering that has to go into a repair like this. In the end, failure to get it right can cause serious consequences for the crew and passengers aboard the 500 should the repair fail in flight.

Below are the pictures of the repair as it progressed from one stage to the other. I hope anyone reading this can appreciate the nature of the repair along with my fascination at the high quality workmanship that went into this repair. This is indicative of all the work that has gone into my 500 to date!

Station 124 Canted Beam before repair work starts

Station 124 Canted Beam before repair work starts

This is the canted beam before they started any repair work on it. You can see both wear marks noted by blue tape here to identify the exact area of damage.


Station 124 Canted Beam after prepping for repair

Station 124 Canted Beam after prepping for repair

This is the canted beam after it had been prepped for its repair. It had to be cleaned, cured and then epoxy primer and adhesive was applied prior to installation of the repair pieces.

Doublers in Place

Doublers in Place

Here you can see that the doublers and shims needed for the repair have been put into place and they have started to install the rivets and Hi-Lok pins that will hold the entire repair in place.

View of work from other side

View of work from other side

Here is a view of the repair work from the other side of the picture above. You can see the bottom row of rivets/Hi-Lok pins are already in place and the epoxy adhesive is also visible.

And now you can see the extent of the completed repair:

Completed Repair

Completed Repair

Completed Repair

Completed Repair

Completed Repair

Completed Repair

Completed Repair

Completed Repair

Now I don’t know about the rest of you, but I feel much better with this style of repair over my “80 grit and some white rustoleum” repair. And if you happen to see a grey BWM with a white streak across the hood driving around Mesa one day, you will know that’s me!

Richard J. Sears

Hi – I am the author – Richard Sears. I have been a pilot and flight instructor for over 20 years!

If you live in the San Diego area and would like to arrange a free airplane or helicopter flight for your child (age 8 to 18) through the EAA Young Eagles program please email me at richard@sears.net

If you are a Scout Master, I can work with your troop on the Aviation Merit Badge and provide all ground training and flights necessary to meet the latest requirements of the Aviation Merit Badge. I am a registered Merit Badge Counselor with the BSA San Diego – Imperial Council.

All my flight time is donated, there is no cost to the parents or the troop.

Parents are always welcome to ride along and get hooked!

Hello Everyone – Time to update you on the ongoing restoration project on my MD500e. Phoenix Heliparts in Mesa Arizona has been working very hard on the 500 and we have made great progress in the past month. It is very nice to see the project move along. The project is taking longer than expected only because of additional work that was discovered needed to be done along with additional work I wanted done once the ship was taken apart and inspected. The obvious time to do a repair or upgrade is while the entire helicopter has been torn apart since everything is accessible. Some things (as I said before) simply could not be repaired without taking the ship apart so patches were put in place. All of those patches are now gone and the repairs of those areas have been completed.

As we continue to move forward, it is time to start putting things back together again. Certainly this is more fun that seeing it taken apart just because it means we are that much closer to having a completed ship back in the air!

Part of the process was the removal of the entire autopilot system that had been factory installed when the ship was brand new. Since the system was not a SAS (Stability Augmentation System) and was just a basic autopilot, I choose to have it and all of its brackets, wiring, servos, and controls removed. This saved me about 80 pounds in total weight once everything was removed. Part of the problem when we did that was that the places where some of those items were installed left large gaping holes. This was not really acceptable, so replacement panels were installed to bring the ship back a “pre-autopilot” configuration. Almost none of the metal panels are installed with screws, so all of the work involved removing, replacing and riveting new panels into place.

Here are some pictures of the kick panels below the pilot and co-pilots seats being replaced to cover up where all the controls and brackets had been installed.

Panel Rework

Panel ReworkA

Panel WOrk

Panel Work

As I said earlier in the post, some things we decided to do as part of the process. Strictly speaking these repairs or upgrades were not “necessary” but would make working on the helicopter much easier in the future. One of these items was the installation of “inspection” ports under the pilot and co-pilot’s seats. These inspection ports give the mechanics complete access to all of the controls and wiring under each of the seats without having to tear apart the back seat and try to access these areas under cramped and confined conditions.

Inspection Port under Co-Pilot's Seat

Inspection Port under Co-Pilot's Seat

In this particular case, the actual metal that made up the seat bottom had been cracked, so the co-pilot’s side had new metal installed for the seat area when the inspection port was installed. These type of changes to the helicopter are done under what is called an STC or Supplemental Type Certificate. This allows shops like PHI to modify certain areas of the helicopter under very specific guidelines. This is just one of many STCs that will be installed in the 500 before its all done.

Pilot's Side

Pilot's Side

As you can see from this pictures, the pilot’s side did not have any cracks and therefore did not need to be replaced as did the co-pilot’s side. So the STC for the inspection port was made without having to remove and replace the actual seat skins. In addition to the seat work and the work on the front panels just below the seats, a decision was made to replace the front floor as well. Again the primary reason was that several repairs had been made to the floor to repair cracks. You can see this on both sides of the floor – there is a patch installed on either side.

Old Floor with patches

Old Floor with patches

New floor before drilling

New floor before drilling

New floor getting fitted to 500

New floor getting fitted to 500

New floor fitting and drilling completed

New floor fitting and drilling completed

As you can see, its takes a huge amount of time and effort to replace a bad section. Not only does the new section have to be cut to fit, but hundreds (if not thousands) of precise holed have to be drilled to line up the new metal with the rivet holds underneath the new section so it can all be riveted back into place!  Thousands of man hours will have gone into this project, much of it having to do with sheet metal work like you see here. In the same area, the entire front panel was replaced as well. It had additional holes that had been drilled into it over time as well as some patches. Since the entire floor was removed, it was the best time to do the replacement.

Front panel replacement

Front panel replacement

Installing the new front panel

Installing the new front panel

Once these items are all installed or are ready to be installed, the inside of the control box (below the floors and seats) are painted a bright white which will allow for the greatest amount of contract once the controls have been repainted and reinstalled. The controls will be painted a bright yellow allowing for maximum contrast with the white.

Painting

Painting

Painting

Painting

This painting is done so that the bottom skins of the helicopter can be reinstalled. Attempting to paint this area with the bottom skins on would yield less than perfect results, so often times you will see small areas of the helicopter primed or painted while different skins have been removed to allow the best coverage of paint/primer in these areas!

Now that the front area is pretty much taken care of, its time to move back to the rear passenger area of the helicopter. In an earlier post I showed that we removed the fuel bladders. The area where the fuel bladders sit is directly below the passenger floor area. Again, a decision was made to remove the entire floor area as well as the bottom skins in this area. This was done for several reasons. First, the fuel bladder had some holes in it caused by chafing. The best way to address this was the removal of the floor and bottom skins. Otherwise all work would have to have been done via two small holes, again not the best option here.

Removal of the rear floor

Removal of the rear floor

Those two small holes you see in the floor are the holes where you would have to work if you were not taking the helicopter apart. By removing the floor and the belly skins PHI has complete and unrestricted access to the fuel bladder area as well as the fuel bladder liner which will need to be inspected and repaired or replaced if necessary. Special attention is paid to the prep work in this area since the goal is not to have another fuel bladder leak ever again!

Bottom skins being removed

Bottom skins being removed

Bottom Skins Removed

Bottom Skins Removed

Rear floor removal

Rear floor removal

Rear floor and cross braces removed

Rear floor and cross braces removed


Here is the rear floor and all of the cross braces that have been removed from the back passenger area allowing unrestricted access to the fuel bladder containment area. The cross braces are in excellent condition and will be reused, the floor however will be replaced with a new, thicker piece of metal. This will increase floor strength as well as add strength to the helicopter overall. Below you can see the fuel bladder liner before its removal. It will be removed, inspected, repaired and reinstalled with additional care given to making sure it ends up as smooth as possible. This is what the fuel bladders rest on once reinstalled in the floor.

Fuel cell liner

Fuel cell liner

Once all of the floor, bottom skins and fuel liners have been removed, its time to ship the helicopter to MD and have this entire area primed so the bottom skins, fuel liner, floor and eventually the fuel bladders themselves can be reinstalled in the helicopter.

Rigged for priming

Rigged for priming

Rigged for priming

Rigged for priming

Unprimed fuel containment area

Unprimed fuel containment area

The 500 was sent over to the paint booths at MD and the fuel area was primed and then the ship was returned back to PHI where they started working on putting the floor and skins back on the ship.

After priming

After priming

After priming

After priming

After priming

After priming

Getting floor ready to reinstall

Getting floor ready to reinstall

Well, as you can see there is a lot of stuff that has been done to the 500 since my last update. The project is progressing and we are moving towards the “putting it back together” stage of the project. As each item goes back on the helicopter I am getting more and more excited as we watch her back together again! We still have a long way to go before we are done, but we are making progress and that is the name of the game. Now that we are actually starting to put stuff back on the helicopter, the chances of finding anything additional that needs to be done to the airframe is minimized. This means that maximum effort by PHI is being put towards the reassembly of the ship as opposed to finding everything possible that can be found and fixing those items.



Richard J. Sears

Hi – I am the author – Richard Sears. I have been a pilot and flight instructor for over 20 years!

If you live in the San Diego area and would like to arrange a free airplane or helicopter flight for your child (age 8 to 18) through the EAA Young Eagles program please email me at richard@sears.net

If you are a Scout Master, I can work with your troop on the Aviation Merit Badge and provide all ground training and flights necessary to meet the latest requirements of the Aviation Merit Badge. I am a registered Merit Badge Counselor with the BSA San Diego – Imperial Council.

All my flight time is donated, there is no cost to the parents or the troop.

Parents are always welcome to ride along and get hooked!