UNDERSTANDING & COMBATING AGINGLarry Hoffman Field Liaison Engineer Team Lead Aviation and Missile...

1 Yourfilename.pptApproved for public release; distribution unlimited. Review completed by the AMRDEC Public Affairs Office 21 Oct 2009; FN4264.

October 26, 2009

Presented by:Larry Hoffman

Field Liaison Engineer Team LeadAviation and Missile Research, Development

and Engineering Center

Presented to:DOD MAINTENANCE SYMPOSIUM

Phoenix, AZ

UNDERSTANDING & COMBATING AGINGHIGH OPTEMPO/HARSH

ENVIRONMENT

DISCLAIMER: Reference herein to any specific commercial, private or public products, process, or service by trade name, trademark, manufacturer, or otherwise, does not

constitute or imply its endorsement, recommendation, or favoring by the United States Government. The views and opinions expressed herein are strictly those of the authors

and do not represent or reflect those of the United States Government.

Presenter

Presentation Notes

No one can seriously question that US Army aviation combat operations have had an effect on the rate of wear on our aircraft. From a flying hour perspective, the rate of wear may have changed due to combat associated damage and quality of the maintenance during combat operations. But from a calendar year perspective just the op tempo alone has increased fatigue of affected structure. At the same time the Army has instituted strategies to combat this increased fatigue. The Recap program has resulted in overhauled airframes with new and improved structure that has increase fatigue resistance. The Reset program has incorporated some but not all of the same improvements. The purchase of new aircraft has also increased the average remaining fatigue life of the fleet. It's clear that with the increased op tempo, higher gross weights and higher airspeeds associated with combat, damage from enemy fire and finally damage during landings due to unfamiliar terrain and stress of combat on the pilots, the war is definitely taking a heavier toll on our aircraft than as if we were not at war. But, the helicopters are built such that we could replace almost the entire airframe if necessary, and keep the same aircraft almost indefinitely. The aircraft certainly age, but they can also be made new, at a cost. That is how we have kept the Hueys and 58's around forever. The D model Chinooks though has become so crack prone, upgrade to the F was almost mandatory. Combat definitely hastened the replacement of the Chinooks. Due to the construction of the Apache, it too may become difficult to maintain later in its life. The UH60 has proven to be pretty field repairable. But we are already seeing many cracks in its structure. There may be a point where the older UH60's become too expensive to maintain. But with upgrades they may fly another 50 years. There is no question the war has hastened degradation of the airframes, and almost certainly increased maintenance expense per flying hour, if not also shortened the effective life of the aircraft. This office does not have the data though to positively support these arguments. The data probably is available by compiling information from multiple sources, such as the Reset office, the PM's, the manufacturers, ACE (this office) and the Engineering Support System (MEC data, this office). Factors to consider when evaluating the attached charts: Factors affecting MEC count: o War - optempo, combat intensity, size of forces - more damage - more MEC's - Info on optempo, size of forces should be available from the PM's o Reset - in addition to normal phase inspections. More maintenance - more MEC's - Info on Reset available from AMCOM G3 - Avn Field Maint Dir (AFMD - COL Evans) - Reset Office collects a tremendous amount of discrepancy data during Reset o LAR U - trained LAR's to submit MEC's - to obtain MEC's from the engineer; started in last 5-7 years - Info on LAR U from AMCOM Dir Readiness o LE program growth (explosive) - tripled during this period. Easier for the field to get MEC's. o MEC program success - as # of MEC's increased - units demanded MEC to cover more situations o Aging aircraft probably require more MEC's to maintain - to perform limited depot airframe repairs Factors affecting aging: o Optempo o Maintenance intensity & quality o Combat ops - enemy fire, high airspeeds, high gross weights, ops in unfamiliar terrain resulting in landing damage, combat stress resulting in landing damage. o Improvement to acft (Reset, Recap, Limited depot repairs) o Recommend contacting Reset, Platforms for more data Factors affecting Reset o Stay behind aircraft - aircraft left in COC (overseas) multiple years decreased Reset volume in 2007? o Contact Reset/AMCOM G3 AFMD Factors affecting ACE o Points (weights) assigned to airframe damage indicators change over time o Individuals performing evaluations o number and frequency of evaluations o contact this office for more info.


Combat Operations in harsh environments are significantly affecting the aging of the US Army Rotary Wing Fleet. And the US Army has responded to Combat this increased aging

Recap/Overhaul, New Acquisition, Modifications and Improvements, Parts Life Adjustments, Intensive Technical and Logistical Support, Reset, Condition Based Maintenance, and Aircraft Condition Evaluation are the tools the Army is using to ensure Readiness, Safety & Lethality – Mission Success

UNDERSTANDING & COMBATING AGINGHIGH OPTEMPO/HARSH ENVIRONMENT


US ARMY ROTARY WING IN CONTINGENCY OPS

• OPTEMPO- often near max sustainable - 3 to 6 times non-contingency• GROSS WEIGHTS – often at max• AIRSPEEDS – often at max• G LOADS / FLIGHT PROFILE - pushing the envelope with combat &

evasive manuevers• FOG OF WAR – more likely to push or exceed parameters• UNFAMILIAR TERRAIN - more likely to damage acft during landings• SAND AND DUST

– More likely to damage aircraft during landing– Higher wear on components

• HEAT, COLD, ALTITUDE – near or exceed max parameters• MAINTENANCE

– Must be performed in minimal time– Environment often hostile


Presenter

Presentation Notes

No one can seriously question that US Army aviation combat operations have had an effect on the rate of wear on our aircraft. From a flying hour perspective, the rate of wear may have changed due to combat associated damage and quality of the maintenance during combat operations. But from a calendar year perspective just the op tempo alone has increased fatigue of affected structure. At the same time the Army has instituted strategies to combat this increased fatigue. The Recap program has resulted in overhauled airframes with new and improved structure that has increase fatigue resistance. The Reset program has incorporated some but not all of the same improvements. The purchase of new aircraft has also increased the average remaining fatigue life of the fleet. It's clear that with the increased op tempo, higher gross weights and higher airspeeds associated with combat, damage from enemy fire and finally damage during landings due to unfamiliar terrain and stress of combat on the pilots, the war is definitely taking a heavier toll on our aircraft than as if we were not at war. But, the helicopters are built such that we could replace almost the entire airframe if necessary, and keep the same aircraft almost indefinitely. The aircraft certainly age, but they can also be made new, at a cost. That is how we have kept the Hueys and 58's around forever. The D model Chinooks though has become so crack prone, upgrade to the F was almost mandatory. Combat definitely hastened the replacement of the Chinooks. Due to the construction of the Apache, it too may become difficult to maintain later in its life. The UH60 has proven to be pretty field repairable. But we are already seeing many cracks in its structure. There may be a point where the older UH60's become too expensive to maintain. But with upgrades they may fly another 50 years. There is no question the war has hastened degradation of the airframes, and almost certainly increased maintenance expense per flying hour, if not also shortened the effective life of the aircraft. But the US Army is pursuing a multi-frontal approach to ensure aviators have the safest, highest performance equipment possible for battle.


FLEETWIDE MITIGATION EFFORTS• On-site Engineering – field liaison aerospace engineers• TASM/AVCRAD - Theater maintenance enablers• Re-evaluate flight load surveys – revise life limits, redesign,

investigate life enhancement/extension, revise flight envelope – pitch roll limitations

• Fleet Age reduction– UH60M, CH47F, AH64D Block Mods, O/H & Recapitalization

• Airframe and component upgrades and modifications• Reset – heavy phase, limited depot level airframe repairs &

limited modifications• CBM – Condition Based Maintenance• Assessment of Stay Behind Equipment (SBE) – ACE• Airframe Condition Evaluation (ACE)



LIAISON ENGINEERING

IMBEDDED AMRDEC

Address unique maintenance & reliability issues in real time


46 US Army Aviation Engineering Directorate (AED)Aerospace Engineers deployed since February 2003


O/H & RECAPITALIZATION (Recap)

– Make the aircraft like new.– Recap adds updates/improvements – make

better than new.– Increased structural reliability– Improved time-on-wing for components– Improved performance– Reduced maintenance burden to the field– Diminished opportunity for structural cracking– Results reflected in Airframe Condition

Evaluation (ACE) O/H & Recap



RESET

• Phase +• Heavy cleaning• Med-Heavy Airframe• Mods


Restore aviation equipment to a fully mission capable condition in accordance with AR 700-138 using special technical inspection and repair procedures outlined in Army Technical Bulletins (TBs). Assist Program Managers in fleet configuration control through the application of outstanding Modification Work Orders (MWOs) and perform limited depot repairs.


CBM – Condition Based Maintenance• Combating Aging and Operating Smarter• Seeded fault testing• Monitor components using Modernized Signal Processor

Unit (MSPU) or Vibration Management Unit (VMU) under Vibration Management Enhancement Program (VMEP)

• Component failures and health predicted based on real-time or near real-time monitoring

• Repair/Replace components based on actual condition • Reduced downtime and increased readiness



Condition Based Maintenance Example• MSPU aircraft was reported to have CIs in the red threshold and requested guidance from AED. • The CIs indicated a potential fault within the Tail Rotor Swashplate bearing. AED recommended the removal of the Tail Swashplate and to have the Unit submit a CAT I QDR to investigate the root cause of the vibration. Tail Rotor Swashplate Bearing had only 69 Hours TSN.



TR Swashplate Ball Bearings were pitted

Heavy Spalling on Inner Race

Heavy Cage Wear

Several sources were identified that would generate the abnormal vibrations during Tear Down Analysis.



4-227th Aircraft 03-05371 was reported to have experienced a Transmission Chip Indication with vibration felt by the pilots, oil leaking from the APU Drive Shaft Input Flange, and the Input flange having excessive play; however, no MSPU PC-GBS indication of an impending failure was provided to the Unit.

AH64 03-05371 XMSN 229 Gear Bearing

Last set of data the unit saw after the XMSN Chip Indication

XMSN CIs

APU with Drive Shaft Monitoring CIs


AH64 03-05371 XMSN 229 Gear Bearing TDA Photos

Damage focused to one side of rotating inner race

The Transmission was removed from Aircraft 03-05371 and sent to RTTC for a Tear Down Analysis. Preliminary TDA results show likely source of the chip Indication came from 229 Gear outboard Bearing.


AH64 03-05371 XMSN 229 Gear Bearing

σ

σ

5 Months of Data presented here prior to Aircraft XMSN Chip Light

229 Gear Bearing Characteristics:3 BPFI 2261.68Hz

Accessory Reduction Ball Characteristics:3 BPFI 2300.86Hz4 BPFO 2376.82Hz


CBM Seeded Fault Test Facilities

ARL Accelerated Test StandUSC Test Stand Drive Train and M/R Swashplate Stand

RAPTR APU & Clutch Test Stand ARL Bearing Signature Test Stand


AIRFRAME CONDITION EVALUATION – ACEEvaluating the Fleet – Assessing our Actions



ACE Analysis

• ACE is an annual assessment of the fleet to gather data on the structural condition of the aircraft.

• The assessment results in a numeric score for every aircraft. The higher the score the worse the condition of the airframe. The score is the result of adding points assigned to various types of defects identified during the assessment.

• Scores for each mission design series (MDS) are unique to that series. A numeric score from one MDS cannot be compared to the numeric score of another MDS.

• ACE data is used to identify candidates for depot repair and to identify symptoms of airframe corrosion, overstress and fatigue

•Data collected during evaluations is stored in the ACE database and is used for technical and logistical analysis. ACE is a management tool as well as an engineering tool.


Conclusions

• The overall ACE score averages stay fairly consistent from year to year

• Aircraft that have gone through Reset showed lower average scores in subsequent evaluations when compared to non-reset aircraft

• Aircraft that have gone through Recap showed significantly lower average scores in subsequent evaluations when compared to non-Recap aircraft


SUMMARY

Combat Operations in harsh environments are significantly affecting the aging of the US Army Rotary Wing Fleet. And the US Army has responded to Combat this increased aging

Recap/Overhaul, New Acquisition, Modifications and Improvements, Parts Life Adjustments, Intensive Technical and Logistical Support, Reset, Condition Based Maintenance, and Aircraft Condition Evaluation are the tools the Army is using to ensure Readiness, Safety & Lethality – Mission Success



Presented by:Larry Hoffman

Field Liaison Engineer Team LeadAviation and Missile Research, Development

and Engineering Center

Presented to:DOD MAINTENANCE SYMPOSIUM

Phoenix, AZ

UNDERSTANDING & COMBATING AGINGHIGH OPTEMPO/HARSH

ENVIRONMENT

UNDERSTANDING & COMBATING AGINGLarry Hoffman Field Liaison Engineer Team Lead Aviation and Missile...

Documents

Transcript of UNDERSTANDING & COMBATING AGINGLarry Hoffman Field Liaison Engineer Team Lead Aviation and Missile...