# Airmotive Engineering 

# AEC631397 Cylinder Assemblies Development of an Operational 

# Safety Program FAA Review 6
- 1
- 2011

# Discussion Topics

• Review and Identification of COS Groups



# • Identify Essential Elements of COS Program

– Proposed MSB



# • Weibull Statistical Analysis

– Assess Usage Rates, Field Operation Influence, Maintenance Influence



# • Summary & Observations of Weibull Analysis



# • Recommendations

– Define MSB

– General Field Action
6/1/2011 2 D. Kenton

# Review

• 33 Reported Separations of Cylinders

– August 2002 through July 2010



# • Cylinder Head/Barrel Separations from Fatigue

– Head fillet radius
– improper heat treatment



# – Head fillet radius
– inherent design deficiency

– First loaded thread
– inherent & induced design deficiency



# – Not confined to AE units (Sky Ranch Manual)



# • Cylinder Wall Cracking

– not causing separations 6/1/2011 3 D. Kenton

# Review (ctd)

• Adjustments

– MSB4
- 1 to recall improperly heat treated units

– MSB6
- 2 to address wall cracks

– Revised head casting to (AEC65385 Rev. E) to 

# increase wall thickness

– Increased head fillet radius to eliminate radius fatigue cracking



# – Introduced intake valve seat with Allison back to increase intake side head wall thickness

– Increased interference fit to relieve thread loading
6/1/2011 D. Kenton 4

# Review (ctd)

• Key Design Parameters

– Interference

• By measurement of TCM units

• Measured 0.01 to 0.012

- inch at shrink band



# • Minimal at threads



# – Interface Temperature Design Point

• Test data from similar design



# • Head temperature near barrel 405F at CHT = 460F

• Barrel temperature adjacent to head 360F at CHT = 460F

• Assumed design point at 375F 6/1/2011 D. Kenton 5

# Review (ctd)

• Previous Key Findings and Recommendations

– Significant influence of field servicing and operation

– Found Through Additional Review of Data

• AE Cylinders replicated OEM design



# • AE replication and embodiment of design incorporated inherent deficiencies of the OEM

6/1/2011 D. Kenton 6

# Review (ctd)

• Previous Key Findings and Recommendations

– Group MSB6
- 2, SN1 – 33689
- 24

• Date Range: 9/1/02
– 11/29/05

• A small number of units had elevated risk of radius 

# fatigue

• Modify MSB6

- 1

– Include fins 4

- 7 & 9
- 10 for visual crack inspection

– Remove all 4

- 1 and 6

- 2 units at next teardown

– Scrap all removed cylinders

6/1/2011 D. Kenton 7

# Review (ctd)

• Previous Key Findings and Recommendations

– Group Post MSB6
- 2, SN 33690
- 01 – 64016
- 27

• Date Range: 12/1/05
– 10/12/09

• Small % of units at elevated risk thread fatigue

• Issue MSB similar to MSB6

- 2

– Begin repetitive inspections at within next 50 hours

– Include fins 4

- 7 & 17 for visual crack inspection



## – Remove all Post 6

- 2 units at next teardown

– Scrap all removed cylinders

6/1/2011 D. Kenton 8

# Cylinder Groups for COS Discussion GROUP QUANTITY RETURNS SEPARATIONS NET MSB6 - 2 16,187 756 25 15,406 PMSB6 - 2 20,937 40 8 20,890 TOTALS 43,767 796 33 42,938 Note: 4,501 PMSB6 - 2 produced with Allison Back Intake Valve Seats

6/1/2011 9 D. Kenton 

### MSB6
- 2:
• AEC65385 rev. D
- Cylinder head wall at fin 17
• 0.030 - inch fillet radius PMSB6
- 2


### • AEC65385 rev. E

– Increase cylinder head wall at fin 17
• 0.045 - inch fillet radius

# Essential Elements of a New MSB

• Identify groups by serial number range

• Inspect for problem cylinders

– Remove improperly operated or damaged units



# • Mitigate field operation and servicing factors

– CHT systems

– EGT systems

– Cooling Baffles

– New Cylinder Installation and Break

- in

6/1/2011 D. Kenton 10

# Weibull Analysis

• Develop Bracketed range for risk assessment

– From Report 1102
- 13

• Actual to Standard Mean = 2.9

• Coefficient of Variation = 1.21



# – For Comparative Analysis Use a Ratio of 2

• Standard use = 100 hr/yr

• Accelerated use = 200 hr/yr



# – Basis

• All reported failures considered separations

• TIS is reported time in service (hours)



# • Assume radius failure prone units removed 6/1/2011 D. Kenton 11

# Actual/Standard Hours Correlation

6/1/2011 D. Kenton 12 

### 0 200 400 600 800 1,000 1,200 1,400

0 200 400 600 800 1,000 1,200 1,400 Time in Service Hours



### Standard Hours

# Weibull Analysis (ctd)

• Consideration Factors Group MSB6

- 2

– Last failure date 7/14/10

– All failed units produced and shipped in 2004



# – 18 of 21 failures occurred at less than 500 hours

– Maximum fleet time = 763 to 1546 hrs

– Minimum fleet time = 508 to 1016 hrs



# – Characteristic life of radius failures about 1200 hr

– Explore field service and operation influence

6/1/2011 D. Kenton 13

# Weibull Analysis (ctd)

• Consideration Factors Group Post MSB 6

- 2

– All observed failures were in first loaded thread

– Three failures exceeded fleet use rate by at least 

# 60% to as much as 220%

– Short time suspensions affect Weibull curve shape

– 4500 units produced with heads having increased 

# intake side will thickness (use of intake seats with Allison style back)

– Explore field service and operation influence

6/1/2011 D. Kenton 14

# Weibull Analysis (ctd)

Group MSB 6 - 2 Evaluation MSB6 - 2 MSB6 - 2 thru 2004 100/yr 200/yr 100/yr 200/yr Consol. Consol. Consol. Consol. Var. A Var. A Var. A Var. A 

## Var. B Var. B Var. B Var. B 

# Group Post MSB6 - 2 Evaluation P MSB6 - 2 P MSB6 - 2 + 2005 100/yr 200/yr 100/yr 200/yr Consol. Consol. Consol. Consol. Var. A Var. A Var. A Var. A 

## Var. B Var. B Var. B Var. B 6/1/2011 D. Kenton 156/1/2011 D. Kenton 16



# Weibull Function

= Fraction failing up to time, t (CDF) = Failure time 

# = Slope or shape parameter =Characteristic life or scale parameter6/1/2011 D. Kenton 17 

# Weibull Analysis (ctd)

# Weibull Analysis (ctd)

6/1/2011 D. Kenton 18

# Weibull Analysis (ctd)

6/1/2011 D. Kenton 19

# Weibull Analysis (ctd)

6/1/2011 D. Kenton 20

# Weibull Analysis (ctd)

6/1/2011 D. Kenton 21

# Weibull Analysis (ctd)

6/1/2011 D. Kenton 22

# Weibull Analysis (ctd)

6/1/2011 D. Kenton 23

# Weibull Analysis (ctd)

6/1/2011 D. Kenton 24

# Weibull
– Group 6
- 2 Summary

6/1/2011 D. Kenton 25 

## GROUP VAR. ETA BETA B = .1% B = .5% 6
- 2 (100/YR) A 12,537 1.998 396 886 B 4,839 3.803 787 1202 6
- 2 (200/YR) A 12,537 1.998 396 886 

## B 11,746 2.791 989 1762 6
- 2 THR. 2004 (100/YR) A 10,097 1.999 319 714 B 5,840 3.367 751 1211 6
- 2 THR. 2004 (200/YR) A 10,111 1.999 319 714 B 10,070 2.791 848 1510

# Weibull
– Group P6
- 2 Summary

6/1/2011 D. Kenton 26 

## GROUP VAR. ETA BETA B = .1% B = .5% P6
- 2 (100/YR) A 147,796 1.361 924 3,021 B 1,087 8.903 500 600 P6
- 2 (200/YR) A 1,265,527 1.055 1,818 8,372 

## B 1,123 28.81 884 935 P6
- 2 + 2005 (100/YR) A 342,790 1.244 1,330 4,858 B 1,108 6.143 360 468 6
- 2 + 2005 (200/YR) A 1,613,961 1.049 2,228 10,354 B 2,380 9.332 1,121 1,332

# Weibull Analysis Observations

6/1/2011 D. Kenton 27 

# • Splitting data points improves fit



# • Higher baseline use identifies influence of field operation and maintenance

• Shifting MSB6

- 2 year 2005 to Post MSB6
- 2 isolates all 

# MSB6
- 2 units that were prone to premature separation

• Proposed MSB should be structured to address high 

# and low time MSB6

- 2 units produced through 2004

• Variant A probably represents improper cylinder conditioning

# Weibull Analysis Observations

6/1/2011 D. Kenton 28 

# • Variant B probably represents over temperature 

# operation

• Address Variant A by removing glazed cylinders

– Scrap MSB6
- 2 through 2004



# – Remove and Hone PMSB6

- 2 with less than 75 hours



# • Address Variant B by calibration and maintenance

– Calibrate CHT system and each 24 months thereafter



# – Calibrate EGT system and each 24 months thereafter

– Check and reset all engine cooling devices

# Recommendations for MSB

• Cylinder Serial No.

– 1 through 25526

- 22 = Group A

– 25527
- 01 through 64016

- 27 = Group B


# • Group A Actions

– Cylinders with less than 750 hours TIS

• Initial inspection as defined in this MSB within next 50 hours

• Recurrent inspection each 50 hours as defined in this MSB

• Remove from service at 750 hours



# – Cylinders with more than 750 hours TIS

• Initial inspection as defined in this MSB within next 50 hours

• Recurrent inspection each 50 hours as defined in this MSB

• remove from service within next 250 hours or at next engine teardown whichever comes first 6/1/2011 D. Kenton 29

# Recommendations for MSB (ctd)

• Group B Actions

– Cylinders with less than 1000 hours TIS

• Initial inspection as defined in this MSB within next 50 hours

• Recurrent inspection each 50 hours as defined in this MSB

• Remove from service at 100 hours if CHT system is not calibrated as defined in this MSB

• With CHT calibration continue in service to TBO with repetitive 50 hour inspections



# – Cylinders with more than 1000 hours TIS,

• Initial inspection as defined in this MSB within next 50 hours

• Recurrent inspection each 50 hours as defined in this MSB

• Remove from service within next 50 hours if CHT system is not calibrated as defined in this MSB

• With CHT calibration continue in service to TBO with repetitive 50 hour 

### inspections 6/1/2011 D. Kenton 30

# Recommendations for MSB (ctd)

• Visual and operation inspection

– Confirm serial number and MSB applicability

– Cracks at head fins 17, 5

- 7, and 9

- 10 counting from bottom

– Remove cracked cylinders

– Check for excessive oil consumption

– Check if cylinder(s) has(have) not been installed and conditioned as part of a test cell break

- in procedure

– Check for evidence abnormally high operating temperatures

– Check for proper configuration of cooling baffles

– Check for proper cowl flap operation if installed

6/1/2011 D. Kenton 31

# Recommendations for MSB (ctd)

• Cylinder compression check

– Check per ECi TN 10

- 4

– Soap bubble leak check as needed (Ref, TCM SB 96

- 12)

– Remove cracked cylinders



# • Crankcase Pressure Test

– If excessive oil consumption (1 qt/3 hour)

– If any of the installed cylinders have not been conditioned in a test cell

– Conduct test as defined by TCM Service Bulletin M89

- 9

6/1/2011 D. Kenton 32

# Recommendations for MSB (ctd)

• Crankcase Pressure Test (ctd)

– Remove cylinders if crankcase pressure exceeds limit

– Group A cylinders

• remove from service



# – Group B cylinders with less than 75 hours in service

• Remove, hone, install, and properly break

- in



# – Group B cylinders with more than 75 hours in service



# • Remove from service

6/1/2011 D. Kenton 33

# Recommendations for MSB (ctd)

• CHT System

– Calibrate instrument and thermal probe

– At initial inspection and each 24 months or 200 hours thereafter



# – Standard ASTM calibration procedures



# • EGT System

– Calibrate instrument and thermal probe



# – At initial inspection and each 24 months or 200 hours thereafter

– Standard ASTM calibration procedures

6/1/2011 D. Kenton 34

# Recommendations for MSB (ctd)

• Engine Cooling Devices

– Inspect all cooling baffles & restore to certificated condition as needed



# – Inspect cowl flap system and reset to certificated condition as needed

6/1/2011 D. Kenton 35

# General Recommendations

• SAIB from Engine Test

– Measure Interface Temp

– Compare proper and improperly conditioned cylinders



# • Fleet CHT System

– Calibrate instrument and thermal probe



## – At initial inspection and each 24 months or 200 hours thereafter

– Standard ASTM calibration procedures



# • Fleet EGT System

– Calibrate instrument and thermal probe

– At initial inspection and each 24 months or 200 hours thereafter

– Standard ASTM calibration procedures



# • Fleet Break

- in Procedures

– Publish standard 6/1/2011 D. Kenton 36

# Supplemental Information

# AEC631397 Cylinder Separations S/N Type Class Engine Shipped Remvd TIS (hrs) Failure Location MSB
4464 - 24 TIST 71.2A IO - 520F 1/20/03 3/31/03 87 radius 4 - 1 4360 - 32 TIST 71.2B TSIO - 520 1/15/03 12/2/08 218.1 radius 4 - 1 5482 - 19 TIST 71.2A 2/14/03 9/3/03 283 4 - 1 7141 - 16 TIST 71.2A 4/14/03 11/15/03 269 4 - 1 7819 - 23 TISN 71.2B TSIO - 520NB 5/23/03 4/23/04 204 6 - 2 8013 - 28 TISN 71.2B 5/19/03 8/12/09 960 radius 6 - 2 12612 - 5 TISN 71.2B TSIO - 520NB 10/10/03 4/28/04 200 6 - 2 13515 - 11 TISN 71.2B TSIO520 - NB 1/5/04 6/15/10 360 thread 6 - 2 13515 - 26 TISN 76.0 IO - 550D 2/5/04 8/12/08 338 thread 6 - 2 13670 - 3 TISN 71.2C 1/22/04 4/18/06 1301 6 - 2 6/1/2011 D. Kenton 38

# AEC631397 Cylinder Separations (Ctd)

6/1/2011 D. Kenton 39 

## S/N Type Class Engine Shipped Remvd TIS 

## (hrs) Failure 

## Location MSB
16757 - 6 TISN 71.2B TSIO - 520NB 4/1/04 3/18/05 475 6 - 2 18700 - 1 TISN 71.2A IO - 55F 6/17/04 5/1/09 663 thread 6 - 2 19441 - 28 TISN 71.2A IO - 520D 7/23/04 6/5/07 290 6 - 2 20940 - 22 TISN 76.0 IO - 550F 8/19/04 12/12/05 89 6 - 2 21327 - 19 TISN 71.2B TSIO - 520 9/10/04 2/7/05 721 6 - 2 21432 - 10 TISN 71.2C IO - 550C 8/31/04 10/14/08 355 radius 6 - 2 21994 - 21 TISN 71.2B TSIO - 520NB 9/16/04 5/11/06 330 6 - 2 21590 - 14 TISN 71.2C IO - 550B 9/10/04 4/27/09 150 radius 6 - 2 22241 - 24 TISN 71.2B TSIO - 520NB 10/11/04 7/14/10 264 6 - 2

# AEC631397 Cylinder Separations (Ctd)

6/1/2011 D. Kenton 40 

## S/N Type Class Engine Shipped Remvd TIS (hrs) Failure Location MSB
22389 - 9 TISN 71.2B IO - 550B 10/5/04 5/3/06 170.2 6 - 2 22537 - 24 TISN 71.2B IO - 550B 10/5/04 5/3/06 171.7 6 - 2 22838 - 19 TISN 71.2B TSIO - 520WB 10/20/04 3/11/09 390 radius 6 - 2 23217 - 13 TISN 71.2B TSIO - 520NB 10/19/04 12/30/08 257 radius 6 - 2 23343 - 15 TISN 71.2B 10/26/04 8/1/05 505 6 - 2 23258 - 14 TISN 71.2B TSIO - 520 11/1/04 5/18/08 423.9 radius 6 - 2 33947 - 29 TISN 71.2C IO - 550B 11/22/05 11/20/08 210 thread p6 - 2 34684 - 13 TISN 71.2C IO - 550A 11/6/05 10/1/10 1061 p6 - 2 35955 - 22 TISN 71.2B TSIO - 520NB 1/6/06 5/20/09 1163 thread p6 - 2

# AEC631397 Cylinder Separations (Ctd)

6/1/2011 D. Kenton 41 

## S/N Type Class Engine Shipped Remvd TIS (hrs) Failure Location MSB
45312 - 15 TISN 71. 2 TSIO - 520WB 3/2/07 9/12/09 1095 thread p6 - 2 50785 - 26 TISN 71.3B TSIO - 520WB 11/20/07 4/3/09 196 thread p6 - 2 51847 - 12 TISN 71.2B TSIO - 520 1/23/08 7/30/10 71.2 thread p6 - 2 51973 - 08 TISN 71.2B TSIO - 520 1/28/08 8/4/09 835 P6 - 2 52884 - 22 TISN 76.0 IO - 550F 6/4/08 11/13/08 415.8 thread p6 - 2 Total 33 MSB4 - 1 4 MSB6 - 2 21 Post MSB6 - 2 8

# AEC631397 Not Applicable or Untraceable Cylinder Separations

6/1/2011 D. Kenton 42 

## S/N Type Class Engine Ship Remvd TIS Failure Loc Notes
8009 - 00 FRST 71.2C IO - 550B 12/2/03 1/11/05 409 stripped Freedom 17029 - 28 CCCN 71.2B TSIO - 520 - NB 4/19/04 10/28/09 267 stripped Freedom 31265 - 20 TISN 71.2B IO - 520C 7/27/05 6/15/09 417 stripped Freedom 32803 - 1 TISN 71.2B TSIO - 520M 9/12/09 1095 Freedom? 47932 - 06 TISN 71.2B TSIO - 520VB 7/27/07 10/15/10 1254 NA Repaired 9138 - 00 TISN 71.2A IO - 520 4/6/05 1787 No SN Match UNK - 1 TISN 71.2B TSIO - 520NB 2/23/10 421 UNK - 2 TISN 71.2B TSIO - 520N 3/12/08 105 UNK - 3 O - 470R 2/18/10 151 Not Appl. UNK -- 5 TISN 71.2A IO - 520F 6/21/05 489

# AEC631397 Cylinder Components Group AEC65385

Head AEC631399

Head Threads AEC65414

Head Machining AEC634501

Barrel
MSB4 - 1 C G IR, A 

## N MSB6 - 2 D H A 

## N, P, R, T PMSB6 - 2 E, F K, L C, D 

## U, V PMSB6 - 2 - INT - A F, J N E 

## V

6/1/2011 D. Kenton 43

# Potential Actual/Standard Use Ratio

6/1/2011 D. Kenton 44 S/N Group Shipped Removed TIS (Hrs) STD ()Hrs TIS/STD 4464
- 24 4
- 1 1/20/2003 3/31/2003 87 19.2 4.54 4360
- 32 4
- 1 1/15/2003 12/2/2008 218.1 588.5 0.37 5482
- 19 4
- 1 2/14/2003 9/3/2003 283 55.1 5.14 7141
- 16 4
- 1 4/14/2003 11/15/2003 269 58.9 4.57 7819
- 23 6
- 2 5/23/2003 4/23/2004 204 92.1 2.22 8013
- 28 6
- 2 5/19/2003 8/12/2009 960 623.8 1.54 12612
- 5 6
- 2 10/10/2003 4/28/2004 200 55.1 3.63 13515
- 11 6
- 2 1/5/2004 6/15/2010 360 644.7 0.56 13515
- 26 6
- 2 2/5/2004 8/12/2008 338 452.1 0.75 13670
- 3 6
- 2 1/22/2004 4/18/2006 1301 223.8 5.81 16757
- 6 6
- 2 4/1/2004 3/18/2005 475 96.2 4.94 18700
- 1 6
- 2 6/17/2004 5/1/2009 663 487.4 1.36 19441
- 28 6
- 2 7/23/2004 6/5/2007 290 286.8 1.01 20940
- 22 6
- 2 8/19/2004 12/12/2005 89 131.5 0.68 21327
- 19 6
- 2 9/10/2004 2/7/2005 721 41.1 17.54 21994
- 21 6
- 2 9/16/2004 5/11/2006 330 164.9 2.00

# Potential Actual/Standard Use Ratio

6/1/2011 D. Kenton 45 21432
- 10 6
- 2 8/31/2004 10/14/2008 355 412.3 0.86 21590
- 14 6
- 2 9/10/2004 4/27/2009 150 463.0 0.32 22241
- 24 6
- 2 10/11/2004 7/14/2010 264 575.9 0.46 22389
- 9 6
- 2 10/5/2004 5/3/2006 171.7 157.5 1.09 22537
- 24 6
- 2 10/5/2004 5/3/2006 170.2 157.5 1.08 22838
- 19 6
- 2 10/20/2004 3/11/2009 390 439.2 0.89 23217
- 13 6
- 2 10/19/2004 12/30/2008 257 420.0 0.61 23343
- 15 6
- 2 10/26/2004 8/1/2005 505 76.4 6.61 23258
- 14 6
- 2 11/1/2004 5/18/2008 423.9 354.5 1.20 33947
- 29 p6
- 2 11/22/2005 11/20/2008 210 299.7 0.70 34684
- 13 p6
- 2 11/6/2005 10/1/2010 1061 490.4 2.16 35955
- 22 p6
- 2 1/6/2006 5/20/2009 1163 337.0 3.45 50785
- 26 p6
- 2 11/20/2007 4/3/2009 196 137.0 1.43 51847
- 12 p6
- 2 1/23/2008 7/30/2010 71.2 251.8 0.28 51973
- 08 P6
- 2 1/28/2008 8/4/2009 835 151.8 5.50 52884
- 22 p6
- 2 6/4/2008 11/13/2008 415.8 44.4 9.37 Mean 274.7 2.90 Standard Deviation 196.9 3.51 Coefficient of Variation 0.72 1.21