FAA Bulletin - Tail Rotor Vertical Shaft Inspection

[Steve Chenoweth]

The FAA has issued a Special Airworthiness Bulletin (not mandatory) for tail rotor vertical shafts based on 3 failures this year, apparently due to fatigue. It calls for inspection within the next ten hours of service. Following is the text of the notice. As members of this Forum conduct inspections, please post the results.


SPECIAL AIRWORTHINESS INFORMATION BULLETIN
Aircraft Certification Service
Washington, DC
U.S. Department of Transportation
Federal Aviation Administration
SW-04-90
September 23, 2004
http://www.faa.gov/certification/aircraft

This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin alerts you, owners and operators of Brantly International, Inc., (Brantly), (Hynes) B-2, B-2A, B-2B model helicopters, that four known incidents of tail rotor (T/R) vertical drive shaft failures have occurred, with three of the failures occurring since February 2, 2004.

Background

During an ongoing accident investigation concerning a Brantly Model B2B, we discovered that the T/R vertical drive shaft (P/N 249-10) completely sheared off at the upper bevel gear bolt hole and that the shaft had indications of fatigue cracking. The accident helicopter had a previous incident with a vertical drive shaft failure occurring eleven weeks earlier. Also, there was a more recent incident of different Model B2B vertical drive shaft failing at the same bolt hole location with indications of fatigue cracking. The other known vertical drive shaft failure at the upper bevel gear bolt hole occurred in 1973. The Model B2B involved in the ongoing accident investigation did have a hard landing prior to the two drive shaft failures. Whether this hard landing has a connection to the shaft failure still remains to be verified. There are no known hard landings on the other two helicopters that had shafts fail. We are working with the NTSB and Brantly International, Inc to determine the cause of the fatigue cracking and the best action to correct this unsafe condition. To prevent any further accidents, the following recommendations are provided at this time:
Recommendations
• You should remove the T/R vertical drive shaft (P/N 249-10) from the helicopter within the next ten hours time in service. Then you should disassemble the bevel gear, P/N 15-8, the flange bushing (P/N 15-6), the bolt (P/N 15-201), and the nut (P/N AN 364-1032) from the upper portion of the T/R vertical drive shaft.
• You should eddy current or fluorescent penetrant inspect the T/R vertical drive shaft for cracks at the upper bevel gear bolt hole.
• You should note the total time in service for the T/R shaft since installed new, and note the total time in service for the helicopter.
• You should replace the shaft if cracks are found or indicated.
• You should review records to determine if and at what total hours in service the helicopter may have had any hard landing.
• You should insure that all the hardware is airworthy and that the alignment of the drive shaft is correct during reinstallation.
• You should immediately report your findings to the contact person below whether you find a crack or not.
• You should repeat these recommended inspections after any hard landing. Hard landing inspections and repairs still must be done per the maintenance manual to maintain airworthiness.

For Further Information
Contact Mr. Marc Belhumeur, ASE, ASW-170, FAA Rotorcraft Certification Office, Fort Worth, Texas
76193-0170; phone: (817) 222-5177; fax: (817) 222-5783; email: Marc.Belhumeur@faa.gov

[bryancobb]

Hi Guys:

I removed my T/R Drive Shaft Monday and took it to the NDE inspector today, Wednesday, to get the "Eddy-Current" inspection done.

I'm doing a 100 HR inspection right now so I took the T/R Blades too, to get them Dye-Penetrant inspected. I have the old style so they require the AD Note on them at each 100 HR insp.

He said Max Cost would be $300.00 but that's worst case.

I'll let you know how it comes out!!

Bryan Cobb

[bryancobb]

Hi:

Today I picked up my T/R Blades and vertical T/R shaft from getting them NDI Inspected. They all passed. It cost me 275.00 for the lab-work.

I will assist my A.I. in putting them back on this weekend.

Bryan

[Ron Spiker]

Thanks for the update Bryan. Glad they passed for you. Is anyone else having theirs checked?

[Steve Chenoweth]

I am debating whether to check mine or not. At my last annual, Kevin Hynes ship had already had the shaft fail so the A&P did a close inspection of the shaft, but not with die penetration, and found no problems. My current thinking is to wait for next annual to do the more thorough inspection recommended in the FAA Bulletin.

[Ron Spiker]

I showed this to my A&P and he said that most likely within 6 months or so this will become an actual AD. My annual is just finishing up, but since I've been down for over two months already, I don't think I'm going to have this test done right now. Maybe during the winter when its not nice enough to fly around here.

[maulepilot]

I have the 2001 Brantly B2B with the most recent failure. No hard landing history. It apears it is only on the ones produced by Brantly International in the last few years. My B2b has 350 hours on it. My 1965 B2B has 2000 hours on it and still flying.

Jim

[Ron Spiker]

See the emailed survey request sent out by the factory in the news forum.

[Steve Chenoweth]

I just had my annual and had the tail rotor shaft inspected per the FAA advisory. No problems were found. My B2-B is a 1965 with about 1,800 hours.

Has anyone else had theirs inspected who has not let us know the results?

Thanks,

Steve

[Rotorswing]

Yeh,

My annual was just done, as well.

No problems with the shaft, or anything else.

Brett