US Army Aviation Helicopter Dynamic Components

October 26, 2009Presented by:

Dr. Robert VaughanChief Technology Branch

Structures & Materials DivisionAviation Engineering Directorate

Aviation and Missile Research, Development and Engineering Center

Presented to:DoD Maintenance Symposium

“Understanding and Combating Aging”Phoenix Convention Center, Phoenix, AZ

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US Army Aviation Helicopter Dynamic Components

Approved for public release; distribution unlimited. Review completed by the AMRDEC Public Affairs Office (10/09/09 and FN4254 ).

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CRACKED H-47 SWASHPLATE ROTATING RING

In 2004 routine maintenance discovered a MH-47E Forward Rotating Ring with fatigue cracks during overhaul. This was a first time anomaly. Subsequent inspections have found that ~15% of the Swashplates inspected have these micro cracks near the bearing surface.

Testing, Analysis, and Inspections used to minimize the risk associated with fatigue cracking in the swashplate.

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AH-64D Tail Rotor Scissors Assembly Fatigue Failures

On 30 May 2009, failure of both drive link scissors on AH-64D Apache Aircraft xxx occurred during operational usage.

On 2 Jun 2009, a single knuckle lug of a single TR drive link scissors failed on AH-64D Apache Aircraft xxx during operational usage .

On 8 Jun 2009, a single lug of a single TR drive link scissors failed at the swashplate interface on AH-64D Apache Aircraft xxx during operational usage.

Failure

Failure

Failure

Failure Three failures of the TR drive links were discovered this spring.

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Erosion of Engine Compressors

• T700 Engine Stage 1 Blisk Erosion– Erosion is caused by continuous

ingestion of small hard particles such as sand into engine

– Erosion degrades compressor efficiency and leads to reduced engine performance

RIMFIRE inspection at Corpus Christi Army Depot

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Compressor Erosion Trending

Percentage of Engine/Module Removals Due to Compressor Erosion

T700 Series Engines

From RIMFIRE Database

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Stage 1 Turbine Nozzle Vane Conditions

RIMFIRE inspections at CorpusChristi Army Depot

T700 Engine – 1ST Stage Turbine Nozzle Vanes- Oxidation, Burns and Cracks- Increased Temperature/Performance Criteria

Accelerates Condition Degradation

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Stage 1 Turbine Nozzle Vanes Trending

Percentage of Engine Removals Due toBurns, Oxidation and Cracks of Stage 1Turbine Nozzles

Removal Date

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Stage 1 Turbine Blade Conditions

RIMFIRE inspections at CorpusChristi Army Depot

T700 Engine – 1ST Stage Turbine Blades- Oxidation, Burns and Cracks- Increased Temperature/Performance Criteria

Accelerates Condition Degradation

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Stage 1 Turbine Blade Trending

Percentage of Engine Removals Due to Burns, Oxidation and Cracks of Stage 1Turbine Blades

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Chinook Rotor Systems

Zone J – OD Outside of Limits

– 34.7% rejected due to this condition

Hinge Pin Analysis

RIMFIRE Reports

Zone J

DMWR Limit = 4.5090 inches min.

Average = .0102” under limit

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Chinook Rotor Systems

• 294 Hinge Pins Inspected in RIMFIRE Project

• 121 Rejected by CCAD• 41.2% Reject Rate

Hinge Pin Analysis

RIMFIRE Reports

* Some parts had more than 1 reason for rejection.

Reasons for Rejection Frequency *

1 Zone J - OD Out of Limits 102

2 Zone H - OD Out of Limits 6

3 Zone B - Scoring 4

4 Zone D - Nicks/Wear 3

5 Zone D - Stained 2

6 Misc. Conditions 7

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Black Hawk Rotor Systems

• Zones A & R Damage– 14% of Shafts rejected due to

Chipping/Gouging/Denting in these Zones

RIMFIRE Reports

Zone R

Zone A

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Black Hawk Rotor Systems

• 150 Shaft Extensions Inspected in RIMFIRE Project

• 21 Rejected by CCAD• 14% Reject Rate

Main Shaft Extension Analysis

RIMFIRE Reports

* Some parts had more than 1 reason for rejection.

Reasons for Rejection Frequency *1 Zone R Damage 122 Zone T Damage 73 Zone A - Spline Damage & Wear 44 Zone H - Chipped 15 Zone P - Chipped 1

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Apache Rotor Systems

Zone L

– 37.4% of Pitch Housings did not pass initial DMWR inspection due to incorrect bonding prep.

Pitch Housing Analysis

RIMFIRE Reports

Zone L

This is a repairable condition per DMWR

Zone K

– 32.8% of washers in this zone were debonded and did not pass initial DMWR inspection.

– 24.6% of washers in this zone were missing and did not pass initial DMWR inspection.

Zone K

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• 329 Pitch Housings Inspected in RIMFIRE Project

• 191 Failed Initial DMWR Inspection Criteria

• 58.1% Reject Rate†

• All -15 Pitch Housings with over 300 hours are being Retired at Depot due to 1204 Hour Life Limit.


RIMFIRE Reports

* Some parts had more than 1 reason for rejection.† Prior to any repairs

1 Zone L - Bonding Prep Incorrect2 Zone K - Debonded3 Zone K - Missing Washers4 Zone C Bushing Wear5 Zone F Bushing Wear6 Zone E Liner & Shim Debonding/Wear7 Zone G Bushing Wear8 Zone A Bushing Wear9 Dents & Gouges10 Scored/Scratched

Data collected between 2/5/2005 and 7/16/2007

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Zone C - Wear

– 15.5% of Pitch Housings failed initial DMWR inspection due to inner diameter wear of bushing exceeding max. limit.


RIMFIRE Reports

DMWR Limit = 2.507 in. maxMean Wear = 0.0028 over limit

This is a repairable location.

Zone CFr

eque

ncy

0.0090.0060.0030.000-0.003

10

8

6

4

2

0

Mean 0.002825StDev 0.002807N 36

Normal Histogram of Zone C

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Zone F - Wear

– 14% of Pitch Housings failed initial DMWR inspection due to inner diameter wear of bushing exceeding max. limit.


RIMFIRE Reports

DMWR Limit = 2.507 in. maxMean Wear = 0.0014 over limit

This is a repairable location.See Chart 4 for Location

Zone FFr

eque

ncy

0.0030.0020.0010.000-0.001

9

8

7

6

5

4

3

2

1

0

Mean 0.001428StDev 0.001048N 32

Histogram of Zone FNormal

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Zone B - Wear

– 37.5% of assemblies failed initial DMWR inspection due to inner diameter wear exceeding max. limit.

RIMFIRE Reports

DMWR Limit = 1.628 in. max

Mean Wear = 0.077 over limit

Lower Shoe Assembly Analysis

Zone B

Zone BFr

eque

ncy

0.270.180.090.00-0.09-0.18

25

20

15

10

5

0

Mean 0.07688StDev 0.1135N 40

Histogram of Zone BNormal

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• 48 Lower Shoe Assemblies Inspected in RIMFIRE Project




RIMFIRE Reports


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Zone C - Wear

– 25% of assemblies failed initial DMWR inspection due to inner diameter wear exceeding max. limit.

RIMFIRE Reports




Zone C

Zone C

Freq

uenc

y

0.240.160.080.00-0.08-0.16

30

25

20

15

10

5

0

Mean 0.06699StDev 0.1037N 40

Histogram of Zone CNormal

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• 106 Hub Subassemblies Inspected in RIMFIRE Project



Hub Subassembly Analysis

RIMFIRE Reports


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Zone G - Wear

– 15.1% of Hubs failed initial DMWR inspection due to inner diameter wear exceeding max. limit.

Hub Subassembly Analysis

RIMFIRE Reports



GZone G

Freq

uenc

y

0.0080.0070.0060.0050.0040.0030.002

4

3

2

1

0

Mean 0.005041StDev 0.001388N 15

Histogram of Zone GNormal

Pitting / Corrosion

– 12.3% of Hubs failed initial DMWR inspection due to pitting or corrosion

Documents

US Army Aviation Helicopter Dynamic Components