Blade Blending

AETC Training Use Only. Do Not Use for the Operation, Troubleshooting, or Maintenance of Operational Weapon Systems

AETC Training Use Only. Do Not Use for the Operation, Troubleshooting, or Maintenance of Operational Weapon Systems

Objective 4a

⚫ Using TOs and necessary support
equipment, blend an F117-PW-100 Fan
Blade with no instructor assists.

AETC Training Use Only. Do Not Use for the Operation, Troubleshooting, or Maintenance of Operational Weapon Systems

Overview

⚫ AFI 21-101 par. 11.18

⚫ 1C-17A-2-70GS-00-1

⚫ Blade Features

⚫ Preparation for Low-
Pressure Compressor
(LPC), 1ststage fan blade
assembly

⚫ LPC 1ststage fan blade
inspection and limits

⚫ Airfoil Blend Limits

⚫ Airfoil Root Section

⚫ Platform and Root

⚫ Part Span Shroud

⚫ Leading and Trailing Edge
Bends

⚫ Continue-in-service
Limits

⚫ Follow Up Action

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AFI 21

-

101 par.11.18.

➢ 11.18.1. General. All units will have a comprehensive training program
to ensure technical standards are met, and proficiency is maintained. The
number of individuals authorized to inspect and repair blades should be
sufficient to meet mission requirements and production needs.

➢

11.18.3.1. Formal training, engine blade blending course.

➢ 11.18.3.2. Annual engine blade blending recertification.

➢ 11.18.3.3. 180-day engine blade blending proficiency.

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Safety precautions

– Safety

➢ Observe Warnings, Cautions and Notes in the T.O

– PPE

➢ Gloves

➢ Goggles/Safety glasses

– Corrosion Identification/Control

➢ Beware of corroded hardware

➢ Engine oil and fuel will cause corrosion

– FOD Prevention

➢ FOD can cause injury to personnel and damage equipment

– Composite Materials i.e…cone segments (care not to
cause undue pressure)

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Exposure to corrosive environment

Engine 170686 AFT acoustic liner typical
corrosion
Corroded FEGV spacer screws

6

Corrosion General information can be
found in 1C-17A-23

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Blade Features

• Concave airfoil is the surface or boundary that has a inward
curve. Like looking into a cave or tunnel

• Convex airfoil is surface or boundary that curves outward
• Leading edge is the front portion of the Blade
• Trailing edge is the aft or back portion of the blade as in
direction of air flow from front to back

• Part Span Shroud
• Platform is the flat surface at the bottom of the blade above
the blade root

• Blade root

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Leading edge

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Trailing
Edge

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Part Span Shroud

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11

Platform

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12

Blade Root

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13

Fillet Area

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Multiple Choice

What T.O. are the blending instructions and limits found?

• 1C-17A-2-70GS-00-01

• 1C-17A-2-71GS-00-01

• 1C-C5A-2-70GS-00-1

• 1C-17A-2-71FI-00-1

Multiple Choice

What PPE is required for lending blades?

• Gloves and an apron

• Gas mask and gloves

• Goggles/safety glasses and gloves

• Goggles/safety glasses and an apron

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LPC Preparation

• Preliminary Tasks
• Warning Tag
• Remove inlet cover and install inlet mat
• Stop rotation

• Thrust Reverser Deployment
• Exhaust cover
• Anti-rotation wedge
• Bunny Suit and Inlet Mat before entering inlet

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LPC 1

st

Stage Insp. Limits

• Nicks in or close to leading and trailing edges become
increasingly critical the closer they are to the root of blade

• Damage to part span shroud shall be treated with extreme
caution

• Standard inspection criteria that applies throughout the
inspection procedures

• Blend limits are evaluated from a standpoint of structural
integrity

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LPC 1

st

Stage Insp. Limits

– Blades with a substantial number of repairs or blades
with blends near maximum limits may adversely affect
compressor efficiency and engine performance.

– Blade surface shall be smooth

– Leading and Trailing edge repairs shall be smooth with a
minimum edge thickness

– Blade limits are based on original edge contour, therefore
all blends in one location are cumulative

– Limits apply after blending/repair.

⚫ I.e… if blending a blade will put it out of limits R2
blade.

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LPC 1

st

Stage Insp. Limits

– Blends directly opposite one another on leading and
trailing edge are also cumulative and shall not exceed the
maximum depth of a single leading or trailing edge blend

– Maximum depth blends on leading and trailing edges
shall be separated by minimum distance equal to mean
chordal length (width) of blade

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Mean Chordal length

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LPC 1

st

Stage Insp. Limits

– Total length of leading and trailing edge blends shall not
exceed T.O. limits and there shall not be more than two
blends to a maximum depth limit per blade

– Maximum material removal allowed during blending and
not to actual damage see reference material

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Blends cannot
exceed total length
of 4 inches
cumulatively. Ea.
Of these is 1.25”
in length to = 5”
total

Max

Max

2 max blends
per blade

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AETC Training Use Only. Do Not Use for the Operation, Troubleshooting, or Maintenance of Operational Weapon Systems

LPC 1

st

Stage Insp. Limits

⚫ Airfoil Blend Limits

– Damage shall be blended to T.O. limits specified

⚫ Sustained indentations with compressed material and raised
edges

⚫ Damage with small radius or ragged edges

⚫ Tip curl damage

– Leading and trailing edges

⚫ Cracks or tears are not permitted

⚫ Damage less than T.O. limits in depth need not be blended

⚫ Blend if damage is greater than depth indicated by T.O. limits

Multiple Choice

How do you stop fan rotation?

• Use your hands

• Use your boot

• Thrust reverser/hands/ exhaust covers

• Thrust reversers/exhaust covers

Multiple Choice

How many max depth blends are allowed?

• 1

• 2

• 3

• 4

Multiple Choice

Blends cannot exceed __ inches cumulatively.

• 2

• 3

• 4

• 5

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LPC 1

st

Stage Insp. Limits

⚫ Airfoil Root Section (Fillet)

– Inspect airfoil root section for damage, such as nicks and
dents

• Damage at Leading and trailing edge

• Damage not in critical areas will be blended if it exceeds acceptable
T.O. limits

• Damage with-in critical areas shall be blended if it exceeds acceptable
T.O. limits

⚫ Maintain minimum chord length

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LPC 1

st

Stage Insp. Limits

⚫ Platform and Root Section

– Inspect platform IAW T.O.

– Inspect root IAW T.O.

– Inspect for missing or loose platform seals

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LPC 1

st

Stage Insp. Limits

⚫ Part Span Shroud

– Hard face area

⚫ Cracks

⚫ Excessive wear

⚫ Chipping

– Broken tips

– Shroud to airfoil radius

⚫ Wear caused by adjacent blade shroud

⚫ Damage not exceeding limits may be repaired

⚫ Blend sharp edges

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LPC 1

st

Stage Insp. Limits

⚫ Leading and Trailing Edge Bends

– Bends within limits are acceptable

– Bends exceeding limits, replace blades

⚫ In-Service Limits

– Blades Can continue in service for 25 hrs
after being repaired to specified T.O limits

– Replace blades that exceed these limits

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Follow Up Action

• Document blend repair IAW AFI 21-101

➢AFI 21-101 AMC supp para 11.8.6.4.4 through 11.8.6.4.4.4 states that personnel finding
damage shall fill out AMC form 178 (QRC 238) and notify EM.

• Remove Anti-Rotation Wedge
• Remove Inlet Mat
• Remove Warning Tag
• AFTO Form 95

➢00-20-1 AMC supp para 9.1.1.4.7 Document the AFTO Form 95 if any repair/component
replacement was needed (e.g. blade replacement, blade blending) due to bird strike.

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60 MXG QRC 238

28

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Replace blade when damage is

outside of TO Limits

⚫ Six sets or less cumulative blade replacements.

⚫ Seven sets or more cumulative blade replacements.

– Inspect engine diffuser case prior

– Vibration survey after

– Document AFTO form 95

– Fan blades will be changed in matched sets of, located 180
degrees apart, and must not exceed 1.0 oz. in difference
within a set.

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Matching sets of blades

30

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FOD prevention

Ensuring tools are not left in the inlet area.
Conduct a FOD inspection before and after maintenace.

31

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FIND THE CORRECTIVE ACTION

➢ 0.630 Nick

➢ 0.002 Nick

➢ 0.251 Nick

32

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FIND THE CORRECTIVE ACTION

➢ 0.630 Nick

✓Blend with 3:1 ratio=1.89

➢ 0.002 Nick

✓Damage less than 0.005
inch in depth need not be
blended providing damage
is smooth and material is
not torn. Blend if damage is
greater than 0.005 inch in
depth.

➢ 0.251 Nick

✓Replace Blade

33

AETC Training Use Only. Do Not Use for the Operation, Troubleshooting, or Maintenance of Operational Weapon Systems

Summary

⚫ AFI 21-101 par. 14.14.

⚫ 1C-17A-2-70GS-00-1

⚫ Blade Features

⚫ Preparation for Low-
Pressure Compressor
(LPC), 1ststage fan blade
assembly

⚫ LPC 1ststage fan blade
inspection and limits

⚫ Airfoil Blend Limits

⚫ Airfoil Root Section

⚫ Platform and Root

⚫ Part Span Shroud

⚫ Leading and Trailing Edge
Bends

⚫ Continue-in-service
Limits

⚫ Follow Up Action

Multiple Choice

What is the max depth blend and ratio if damage was found in "area b"?

• 1.5" maximum depth with a ratio of 3:1

• .75" maximum depth with a ratio of 3:1

• .25" maximum depth with a ratio of 10:1

• .5" maximum depth with a ratio of 6:1

Multiple Choice

What is the corrective action if area E has a nick that measures 0.006" or 0.127 mm in depth?

• No action required, it is within acceptable limits

• Flyback not to exceed 25 hours.

• R&R compressor first stage fan blade

• Consult engine management

AETC Training Use Only. Do Not Use for the Operation, Troubleshooting, or Maintenance of Operational Weapon Systems

Objective 4a

⚫ Using TOs and necessary support
equipment, blend an F117-PW-100 Fan
Blade with no instructor assists.