Federal Aviation Agency AC NO: AC 20-52 

Consolidated reprint: 

January 1974 - includes 

Change 1 

MAINTENANCE INSPECTLON NOTES FOR 

DOUGLAS DC-6/7 SERIES AIRCRAFT 

AUGUST 24, 1967 

DEPARTMENT OF TRANSPORATION 

Federal Aviation Administration 
AC NO: AC 20-52’ 

AIRCRAFT 

EFFECTIVE : 

August 24, 1967 

SUBJECT : MAINTENANCE INSPECTION NOTES FOR DOUGLAS DC-6/7 SERIES AIRCRAFT 

1 . PURPOSE. This handbook describes maintenance inspection notes which can 

be used for the maintenance support of certain structural parts of DC-6/7 

series aircraft. 

. 

2 . DESCRIPTION. Maintenance on the wing, fuselage, and empennage structure 

is reviewed with a view toward supplementing information currently 

available.' 

3 l HOW TO GET THIS PUBLICATION. 

a. Order additiona. copies of this publication from: 

Department of Transportation 

Federal Aviation Administration 

Distribution Unit, HQ-438 

Washington, D.C. 20590 

b 0 Identify this publication as: Advisory Circular 20-52, 

Maintenance Inspection Notes for Douglas DC-6/7 Series Aircraft. 

Flight Standards 

AC 20-52 CliG I 

8/24/67 

TABLE OF CONTENTS 

1. Introduction.' 

2. Description., 

3 l Background. 

4 0 General Information. 

5 0 Type of Construction. 

6 0 General Inspection Tips. 

7 0 Nondestructive Testing (NDT). 

APPENDIX 1 

Figure A-l 

Figure A-2 

APPENDIX 2 

Figure B-l 

Figure B-2 

Figure B-3 

Figure B-4 

Figure B-5 

APPENDIX 3 

Figure C-l 

Figure C-2 

Figure C-3 

Figure C-4 Flap Hinge Bracket and Linkage. 

Figure C-5 Outer Wing Panel Attach Point. 

APPENDIX 4 

APPENDIX 5 

APPENDIX 6 

J 

STATION CHARTS 

a. Outer wing and aileron. 

b l Center wing flap. 

c. Fuselage station. 

(2 pages) 

a. Vertical stabilizer and rudder. 

b 0 Horizontal stabilizer and elevator. 

Page i 

FUSELAGE CQ+PONENTS (5 pages) 

Fuselage Major Components. 

Nose Section Assembly Floor Beam 

Structure, Slant Panel Structure, 

and Slant Panel Skin. 

Lower Center Section Assembly 

Center Wing Section. 

Lower Center Section Assembly 

Floor Beams (Stations 412 to 5001 

Fuselage Floor Panels. 

Page No, 

1 

1 

1 

1 

2 

2 

4 

CENTER WING SECTION 

Center Wing Section Spars. 

Lower Center Section Assembly, 

Center Wing Section Structure. 

Center Wing Trailing Edge Fuel 

Tank Spars Corrosion Resistant 

Seals. 

1 

2 l 

1 

2 

(5 pages) 

FUSELAGE STATIONS 

WING STATIONS 

(15 pages) 

(18 pages) 

DC-6/7 MAINTENANCE INFORMATION (11 pages) 
Page ii 

AC 20-52 CHG 1 

7 Jul 72 

Page No. 

* APPENDIX 7 

Figure G-1 

Figure G-2 

Figure G-3 

Figure G-4 

Figure G-5 

Figure G-6 

Figure G-7 

Figure G-8 

Figure G-9 

Figure G-10 

Figure G-11 

Figure G-12 

Figure G-13 

X-6/7 STRUCTURAL INSPECTION ITEMS (21 pages) 

DC+6/7'Fuselage/Empennage. 

DC-6/7 Center Wing, 

Emergency Exit Door Hinges. 

Emergency Exit Hinge Cutouts. 

Crew and Cargo Door Area. . 

Vertical Stabilizer Front Spar to 

Fuselage Attach Fittings. 

Main Entrance Door Area. 

Fuselage Frames at Wing Upper Spar Cap 

Attach Area. 

Horizontal Stabilizer-to-Tail Stub 

Front Spar Attach Fitting. 

Wing Lower Front and Lower Center Spar Caps 

at Wing Station 30. 

Wing Front, Center, and Rear Spar Caps 

at Station 60. 

Lower Front Spar Cap Splice at M.L.G. Drag 

Brace Attach Fitting. 

Lower Center Spar Cap Splice at Station 0. 

1 

9 

10 

11 

12 

13 

14 

15 

16 

17 

l 

18 

19 

20 

21 * 
AC 200 52 

8124167 

Page 1 

1 0 INTRODUCTION. This advisory circular provides maintenance information 

which can be used by mechanics, repair agencies, owners and operators in 

developing maintenance programs, making improvements in existing programs, 

.and conducting inspections and repairs on certain structural parts of 

Douglas K-6/7 airplanes. The material is based, in part, upon information 

made available through discussions with airline personnel who have maintained these types of airplanes for thousands of hours of time in service. 

The intent of the circular is to impart some of this knowledge to other 

interested persons so that it is not lost. 

. 2 0 DESCRIPTION. The circular contains guidance material for performing 

3 l 

maintenance on wing, fuselage, and empennage structure. The information 

has been derived from service experience. It does not comprise a full 

and complete maintenance program for the subject aircraft but should be 

considered as supplemental maintenance data. Included in the circular are 

diagramatic sketches and station identifications of the wing, fuselage, 

and tail. The material concerns general information on corrosion and 

fatigue plus specific inspection notes which stress the examination of'a 

particular structural area,with suggestions as to the method of inspection. 

In addition, there is a listing of selected maintenance difficulties which 

have been reported since 1964. 

. 

BACKGROUND. I 

a. Aircraft Use. The agency has realized that several different types of 

transport aircraft are being phased out of service by some airlines 

because of the availability of newer equipment. Such older aircraft 

are being purchased by other operators who may not be familiar with the 

scope of required maintenance and the means which have been used to 

keep the aircraft in a safe condition. 

b 0 Maintenance "know how", Since maintenance "know how" is not transferred with the aircraft, the new operator generally goes through a 

learning cycle before he is able to rapidly pinpoint the important/ 

critical problem areas of the aircraft. In this respect, identification of known areas where structural problems have been experienced will help in the preparation of an initial maintenance program 

by a new operator. It also can serve as a guide to other operators 

who have not accumulated sufficient service experience to have knowl- . 

edge of all the problem areas of the aircraft. 

4 0 *GENERAL INFORMATION. 

. a. Manufacturer's Bulletins. It must be emphasized .that the manufacturer 

has published several service bulletins concerning the inspection, 

repair, and modification of X-6/7 aircraft. Service Bulletins 406, 

407 (DC-71, 857, and 858 (DC-61 highlight the importance of maintaining structural integrity on high-time aircraft with particular 

reference to areas known to have experienced crack and corrosion 

damage. Operators are urged to become conversant with the 

Par 1 
Page 2 AC 20-52 

8/24/67 

manufacturer's recommendations and make certain that responsible 

maintenance personnel are knowledgeable on the subject. 

b a Airworthiness Directive. It is emphasized that the material in this 

circular does not supersede any of the requirements of airworthiness 

directives issued under Part 39 of the Federal Aviation Regulations. 

5 l TYPE OF CONSTRUCTION. The major structural components of the aircraft 

are- the wing group, tail group, and fuselage group. Appendixes 1 thru 5 

provide detailed views of these components with station identification 

numbers. 

a. The wing group is composed of left and right-hand outer wing sections 

and a center wing section. The wing group is a full cantilever-type 

structure, with channeled ribs, extruded and formed sheet stringers, 

and heavily built-up spars. Each outer wing section consistsof wing 

tip, an aileron, two aileron trim tabs, and a outer wing panel. .The 

center wing section consists of a left and right-hand wing flap, wing 

flap vane sections, and a center wing panel. The portion of the center 

wing section. that passes through the fuselage is integrated with the 

fuselage upon assembly. The center wing section includes the four 

engine nacelles (two on each side of the fuselage). 

b, The tail group is composed of a vertical stabilizer, rudder, rudder , 

trim tab, left and right-hand horizontal stabilizers, left and righthand elevators, an elevator spring tab for each elevator, and two 

elevator trim tabs for each elevator. With the exception of the 

fabric-covered rudder and rudder trim tab, all control surfaces are 

covered with alclad aluminum alloy skin. 

c. The fuselaEe group is an aluminum alloy, semi-monocoque type structure, 

constructed of longitudinal stiffeners, transverse frames and bulkhead, and f lush- rive ted stres sed skin. The fuselage is divide d into 

three main secti ons - the nos e se ction, upper and lower center S ection, 

and tail section assemblies. 

6 l GENERAL INSPECTION TIk. 

A. Visual Inspection. The primary structure of the aircraft is designed 

to provide resistance to variable forces imposed while in operation 

by dispensing the forces through a structural pattern of *'force flow" 

to the primary structural members of t he, w bing and fuselage. Exter 

indicat ions of failure, such as d istor 'ted skin, t ilted or s heared 

'nal 

rivets, and torn, dented, cracked, or corroded skin are usually obvious. 

Wrinkled skin, *'oil cans", and tilted rivets, adjacent to the 

obviously failed area often indicate secondary damage caused by transmission of stress from the failed area. Misalignment of doors and 

panels may indicate distortion of internal structure. Internal 

structural damage, although not always apparent, may be found by 

closely examining the exterior surface. For example: 

Par 4 
AC 20-52 

8/24/67 

Page 3 

(1) Buckled skin between rivets at the end of a stiffener or stringer 

could mean that the last attaching rivet has failed, or that the 

stiffener or stringer is buckled in the area of the skin buckle. 

When a detailed inspection of the failed area is to be performed, 

functional parts should be actuated to determine if the failure 

has caused binding. 

(2) Deep diagonal skin buckles, located over a frame, former,or rib 

could mean the member is distorted. When doubt exists concerning 

internal condition, the area in question should be opened and 

carefully inspected. 

b 0 Fatigue Cracks. Examples of some areas in DC-6/7 series aircraft 

where cracks have been found are shown in Figure 1. Detailed repair 

instructions are provided in manufacturer's service bulletins and 

manuals. 

UPPER and LOWER 

CENTER SPAR CAPS 

CENTER SPAR 

TO FUSELAGE STABILIZER 

FUSELAGE NOSE SKIN 

PASSENGER, CARGO 

and CREW DOOR AREAS, 

HINGE CUTOUTS 

STABILIZER 

TIP ASSEMBLY 

FIGURE 1- AREAS SUBJECT TO FATIGUE CRACKS 

(1) Wing to fuselage attach fittings at center spar. 

(2) Horizontal stabilizer and tail stub front spar attach fittings. 

(3) Fuselage nose skin plating. 

(4) Main crew/cargo entrance door latch plates. 

(5) Rear fuselage frame and transverse floor beams. 

c. Corrosion Prone Areas. Figure 2 refers to some of the corrosion prone 

areas in the aircraft. Manufacturer% service bulletins and manuals 

have been issued to provide detailed repair instructions. 

Par 6 
Page 4 AC 20-52 

g/24/67 

7. NONDESTRUCTLVE TESTING (NDT), 

iANDING GEA 

L--CABIN FLOOR - LR and SUPPORTS 

PASSENGER, CARG 

,?,,,sT PATH AR*?~ CREw D00Rs 

FIGURE 2 - AREAS SUBJECT TO CORROSION DAMAGE 

(1) Exhaust path areas. 

(2) Battery areas and vents. 

(3) Lavatories, galleys, and cabin floors.* 

(4) Wheel wells and landing gear. 

(5) Joints between extruded aluminum sections and laminations. 

Simply stated, nondestructive testing is preventative maintenance. This 

includes utilization of such maintenance tools as X-ray, ultrasonic, magnetic particles, eddy current, and dye penetrant. 

a. Maintenance Inspection. NDT permits maintenance inspections without 

removing components from aircraft or tearing down complex assemblies. 

Defects in various aircraft systems which would escape detection 

through normal visual inspection will be identified by NDT. 

b . Training Required. Special NDT training is necessary to.make sure 

that the operator is capable of operating the equipment and interpreting the results. Also, many states require that an X-ray 

operator have an approved certificate for use of#X-ray in industrial 

applications. This is to minimize improper use of X-ray equipment 

with attendant health hazard. 

Par 6 
AC 20-52 

g/24/67 , Page 5 

AZRCRAFT STATION DIAGRAMS 

The wing, fuselage, and empennage station diagrams included 

in this document were developed for the DC-6B aircraft and 

areused as a general reference only. Several models of each 

of these aircraft were manufactured and have different station 

locator numbers based on the particular configuration. Since 

the defect areas generally apply to all models of both aircraft, the referenced area can be compared with a similar 

area and locator on the appropriate station diagram for the 

particular model of aircraft. For example, fuselage station 

69 on the DC-6A/B may be station 129 on the DC-6 and 29 on 

the DC-7C. 

1 . 

’ . 

NOTE: AILERON SlAtlONS 

SHOWNAT HINGE ?OINV$ A 

& IA8 locATlONs. STATIWSWTBRWWGAAILERON TRIM TAB WA. wsMcTmHllwslRAT8a4s 

462 105l7 DC-6 

FUSELAGE 

LONCERONS 

INSPECTION 

REFEUENCEONlY 

C 

slATloNs iwQuoI 

22 

-13 

-46 

m 

157 

11t 

69 

41 

4 

-29 

42 

W~UIJSTRA~ FUSEUGE STATIONS 

DCdA/B STA 129 (Or-6) dmllor to Sm (DC+ 

STA 69 (DC-t) clmllar b STA 29 (DC-7C) 

780 

736 

101 

661 

621 

581 

WI 

500 

464 

421 

281 

341 

ml 

260 

220 

I70 

I34 

89 

58 

1194 

II* 

Ill5 

1071 

1033 

985 

949 

926 

886 

843 

Ql 
Appendix 1 

Page 2 

AC 20-52 

8124167 

FIGURE A-2 

N&E: RUDDBl STATIONS SHOWN 

ONLY AT HINGE POINTS AND 

TAB LOCATION. 

I-& 

m-wI 

-77 

---- 

w--w 

92 

.-ww--m 107 

E Iw-w- -A- -ma- - lzz 

---w D me- w-w- 13f 

. 

-ma- 

---- - 152 

167 me-- - 

-m--m I# 

----.a P 

m-w- - 191 

---- - 211 

224 

v----m 

m-w- - 238 

- 

69 

ai 

W 

114 

129 

144 

159 

174 

189 

204 

218 

231 

245‘ 

NOTE: ELEVAlat STATIONS SWN 

ONLY AT HINGE POINTS, TAB 

LOCATIONS AND SKIN LAPS. 

a e 

m152 155 

-186 

199 

202 

- --------- - 206 

-- A -219 

B STATDWS 

276 

STATION CHARTS (SHEET 2 OF 2) 
FUSELAGE STATIONS 

STA 129 (DC-6) similar to STA 69 (DC-6A/B) 

STA 69 (k-7)- simi Iar to STA 29 (DC-7C) 

FIGURE B -1 

FIGURE B-3 (SHEET 3 OF 5) 

LOWER CENTER. SECTION 

ASSEMBLY CENTER WING 

SECTION (STA 412 TO 500) 

FUSELAGE MAJOR COMPONENTS (SHEET 1 OF 5) 

DWA/B . 
Appendix 2 

Page 2 

FIGURE B-2 

AC 20-52 

8/24/67 

STA 2 

STA 4 - 

STA 4 - WA22 - STA 41 

~mmmKN 

FIGURE B-2 

NOSE SECTION ASSEMBLY FLOOR BEAM STRUCTURE SLANT PANEL 

STRUCTURE AND SLANT PANEL SKIN (SHEET 2 OF 5) 

DC4WB 
AC 20-52 . 

8124167 

FIGURE B-3 

Appendix 2 

Page 3 

CENTERLINE OF 

FUSELAGE 

SPAR WEB 

SPAIt CAP 

NOTE: 

WEWC 

l CENTER WING STRINGERS AND SPARS HAVE 

SPAR WEB 

6UKHEAD - 

ASSEMLY 

CAP 

BEEN ELIMINATED WITHIN THE CENTER 

FUSELAGE SECTION FOR CLARITY, FUSELAGE STATIONS 

WURE B-3 

STA 129 (DC-6) similar to STA 69 (DC-M/B) 

STA 69 (DC-7) similar to SfA 29 (DG7C) 

LOWER CENTER SECTION ASSEMBLY CENTER WING 

SECTION STRUCTURE DlETAlLS (SHEET 3 OF 5) 

=AIlB 

c -- 
. 

Appendix 2 

Page 4 

FIGURE B-4 

AC 2052 

8/24/67 

STA 412 

FRONT SPAR 

STA 500 FUSELAGE STATIONS 

STA 129 (DC+ similar to STA 69 (DC-6wB) 

STA 69 (DC-7) simila to STA 29 (DC-7C) 

STA 460 . 

TEE 

REM UPPER 

SPAR CAP 

c 

II- EXTRUSION 4 

LOWER CENTER SECTION ASSEMBLY FLOOR BEAMS 

(STATIONS 412 TO SOO) (SHEET 4 OF 5) 

. DC- 
AC 20-52 

B/24/67 

, 

T&xmdix 2 - 

Page 5 

FIGURE B-5 

3 3 3 3 

Gii& m75-0 

SUPPORT 

PLATE 

ST 

FLoa IAbEL 

INSlALLAflOf 

vmw8 SEAT RACKS 

STA 938 

STA 661\ 

s WITH 

FUSELAGE FLOOR PANELS (SHEET 5 OF S) 

DC& 

. 

-- 
-- 
FUSE 

CEN 
LEFT-HAND WING 

WA 60 

FIGURE C-2 

LOWER CENTER SECTION ASSEMBLY CENTER WING 

SECTION STRUCTURE (SHEET 2 OF 5) 

cn 

0 

z 
Appendix 3 

Page 3 

ACZO-52 

8124167 

FIGURE C-4 

FIGURE C-3 

CENTER WING TRAILING EDGE FUEL TANK SPARS AND 

CORROSION RESISTANT SEAL (SHEm 3 OF 5) 
. 

Appendix 3 

Page 4 

-WING FLAP OPERATI I% LINK 

AC 20-52 

B/24/67 

FIGURE C-4 

WING FLAP HINGE SM. 281 

(LOOKING UP AT LOWER 

FLAP HINGE 6JkACKE’I) 

INSPECT ENTIRE CUTOUT AREA OF 

CLEARANCE SLOT FOR CRACKS. 

FIGURE c-4 

FLAP HINGE BRACKET AND 

LINKAGE WING STATION 281 (SHEET 4 OF 5) 


FUSELAGE STATIONS- DC-6/7 AIRCRAFT INSPECTIONS 

FUSELAGE 

STATION 

F.S. 4 

F.S. 18 

F.S. 41 

to 58 

Production 

Break 

F.S. 69 

DESCRIPTION 

skin, framing, pressure bulkhead flanges 

it the windshield Y/" 

slant panel attach 

Joints at the traJerse beam - cockpit 

area 

7uselage skin under 

:he pilot/copilot 

window 

3ulkhead, including 

the surrounding skin 

INSPECT 

FOR 

Cracks 

Loose Internal 

fastener inspection 

cracks/ from cockpit 

corrosion _ area 

Numerous 

cracks 

Cracks, 

loose 

fasteners 

CO~ENTS 

Access for 

inspection 

through nose 

wheel well 

Outside surface (Ref: 

DSBs407 & 

858) 

Remove cockpit soundproofing 

paneling 

INSPECTION 

TOOLS 

Visual (1) This area should receive 

Dye Penetrant frequent inspection. 

Visual 

Magnifying 

glass 

Visual 

Visual 

lo-power 

glass develop 

ment 

-Jul 

REMARKS N 

(1) Particular attention 

should be given to this 

area. 

(2) The stiffener angles 

crack in the attach holes 

F.S. 18. 

(1) Cracks are located along 

the rivet lines and are 

difficult to detect. 

(1) Cracks are located in the 

upper skin/frame areas and 

the lower frame fittings. 

(2) Special repairs have been 

developed for this area. 
FUSELAGE 

. STATION 

F.S. 4 

to 69 

F.S. 41 

to 69 

F.S. 69 

F.S. 69 

NOTE: 

NOTEl.+ 

w* 

FUSELAGE STATIONS - DC-6/7 AIRCRAFT INSPECTIONS cI,'d 4lQ 'd 

v? N9. 

INSPECT 

FOR 

COMMENTS INSPECTION 

TOOLS 

REMARKS 

Fc 

DESCRIPTION 

Cockpit area - floor 

boards 

Nosewheel well. Nose 

gear trunnion 

Battery box cutouts, 

skin and lap joints 

(internal/external) 

Production joint 

attach angle 

Refer to Douglas Serv ce Bulletin 

Close and frequent at 

cockpit area. 

Cracks/. 

Corrosion 

Loose and 

working 

fastener 

cracks 

Cracks/ 

Corrosion 

Cracks 

ention shou 

Floor remove 

None 

Internal 

inspection 0 

the frames 

and stringer 

407 and 858 

1 be given to 

Visual 

Visual 

Visual 

Visual 

Dr additional 

the under floe 

(1) Check for corrugation 

cracks. 

(2)*Check floor beams, frames 

stringers. (NOTE 1) 

(1) Check for black residue 

around inner face of fitting and the rivets. 

(2) Looseness of the trunnion 

fitting may result in 

nose gear shimmy. 

(WIndications of corrosion 

can be found along 

edges of the skin lap, 

rivets along with pitted 

surfaces, blisters. 

(2) Frequent cleaning treatment and protection 

necessary. 

(1) Crack location in metal 

adjacent and inline with 

crew door. 

nformation. 

. cleanliness of the 
FUSELAGE 

STATION 

F.S. 69 

to 134 

F.S. 69 

to 134 

F.S. 69 

to 134 

DESCRIPTION 

Crew door 

Front crew door 

frame, and door 

hinges 

Front crew door hinge 

case 

FUSELAGE STATIONS - D&6/7 AIRCRAFT INSPECTIONS e* h)n 

INSPECT 

FOR 

Rigging 

Cracks/ 

Corrosion 

Cracks 

CWNTS 

Critical 

Remove fuselage around 

door. frame 

None 

INSPECTION 

TOOL 

Visual 

Dye Penetrant 

Visual 

Visual 

lo-power 

glass, Dye 

Penetrant 

(1) Particular attention 

should be given to rigging of bayonets and 

rollers. 

(2) Improper rigging results * 

in excessive wear, cracks, 

and pressurization leaks. 

(1) Critical Area - Cracks 

are located in the aft 

section, upper section 

down midway of door. 

Most critical point is 

located between stringer 

Nos. 10 and 11 approximately to 17" from floor 

line. Also, cracks occur 

in a lower corner of door 

sill. Area prone to 

severe corrosion. 

(1) Crack location - hinge 

line. Area should receive 

close and frequent atten- g + 

tion. D'd 

%% 3 

wrp: 

X 
. 

FUSELAGE STATIONS - D&6/7 AIRCRAFT INSPECTIONS w* P'd OQW 

FUSELAGE 

STATION 

F.S. 69 

to 134 

F.S. 69 

to 134 

F.S. 69 

to 134 

F.S. 89 

to 100 

F.S. 101 

to 118 

NOTE: 

NOTE l.* 

DESCRIPTION 

Intercostals below 

crew door 

Crew door 

Crew entrance door 

jamb 

Stringer No. 31 left 

and right sidefuselage 

Nosewheel well 

tunnel 

1 

'ypical repair instruc 

.igging of the crew dc 

Ixcessive wear, cracks 

INSPECT 

FOR 

Cracks/ 

Corrosion 

Cracks/ 

wear 

Cracks 

Cracks/ 

Corrosion 

Cracks/ 

Corrosion 

:ions may be found in the 

)r bayonets, 

and pressur 

1 CWMENTS 

(Ref: DSBs 

407 & 858) 

None 

Remove lining 

above door 

(Ref: DSBs407 

5c 858) 

rhorough 

cleaning 

prior to 

inspection 

nd rollers is 

.zation leaks, 

INSPECTION 

TOOLS 

Visual and/c 

as required 

Visual 

Visual 

Dye Penetrar 

and X-ray 

X-ray and/or 

as required 

Visual 

SnufacturerQ 

rritical, In 

- 

(1) Close and frequent 

attention should be 

given to this area. 

(l)*Cracks start in the 

bayonet cutouts in the 

door intercostals. 

(NOTE 1) 

(1) Crack location No. 1 

upper forward and No. 2 

upper aft latch cutouts. 

(2) Close and frequent 

inspections. 

(1) Frequent and close 

attention should be 

given to this area. 

(1) Crack location - aft 

lower corners. 

nanua 1. 

roper rigging results in 
I 

FUSELAGE 

STATION 

F.S. 69 

to 400 

F.S. 134 

to 179 

5 F.S. 149 

DESCRIPTION 

c* FUSELAGE STATIONS - DC- 6/7 AIRCRAFT INSPECTIONS tan *h) 

NO m I \Iu 

REMARKS N INSPECT 

FOR 

COMMENTS INSPECTION 

TOOLS 

Fuselage skin, 

longerons, frames 

(belly) 

Cargo door hinge 

cutouts 

Stringers Nos. 28 

and 31 and frames 

Corrosion 

internal/ 

external 

Cracks 

Cracks 

_ . 

Access to 

area through 

front lower 

baggage bin 

None 

Internal/ 

external (Ref 

DSBs 407 & 

858) 

Visual 

X-ray 

Visual 

Visua 1 

X-ray 

Dye Penetrant 

(1) Corrosion located inner - 

and outer sides of fuselage 

skin longerons, frames, and 

skin laps. 

(2) White deposits on edges of 

skin laps, around rivets, 

blisters in paint, pits 

are indications. 

(3) Frequent cleaning and 

treatment necessary. 

(1) Crack location - radius 

of the cutouts and skin 

panel. 

(2) Routine inspection 

necessary. 

(1) Cracks 2 to 7 inches 

found along right side 

stringer. w* w'd cmv 

(2) Cracks are located in v 

bottom row of rivet in qz 

the skin cap. 3c 

F* 
FUSELAGE STATIONS - D&6/7 AIRCRAFT INSPECTIONS 

FUSELAGE 

STATION 

F.S. 178 

to 260 

F.S. 186 

F.S. 178 

to 260 

NOTE: 

NOTE 1: * 

DESCRIPTION 

Fuselage skin lap - 

longeron No. 26 

Fuselage skin lap - 

longeron No. 31 

Lavatory floor and 

floor beams 

Particular attention 

Typical repairs and rn( 

INSPECT 

FOR 

Corrosion 

Loose fasteners 

Corrosion 

Corrosion 

hould be gi 

difications 

COMMENTS 

(Ref: DSBs 

407 ti 858) 

None 

(Ref: DSBs 

407 IL 858) 

Critical 

en to inspectj 

nay be found j 

INSPECTION 

TOOLS 

Visual and/or 

as required 

Visual and/or 

X-ray 

Visual * 

In of magnesia 

1 the manufact 

(1) Located at the skin lap 

just below the forward 

water tank service panel. 

(2) Particular attention 

should be given to this 

area. 

(1) Severe corrosion in this 

area. 

(2) Particular attention 

should be given to this 

area. 

(1) Corrosion located in the 

floor and floor beams. 

Heavyespecially around 

the sink area. (NoTE 1) 

(2) Inspection can be made 

from the forward lower 

baggage bins. 

(3) Popped rivets and paint 

blisters are.external 

indicators. 

L floor beams. 

rer's manual. 
FUSELAGE STATIONS - DC-6/7 AIRCRAFT INSPECTIONS 

FUSELAGE 

STATION 

F.S. 178 

to 260 

F.S. 241 

to 280 

F.S. 261 

to 280 

F.S. 301 

NOTE: ?articular attention s louId be giv 

NOTE I:* Typical repairs and mc 

DESCRIPTION 

Butt joint - hydrauli 

compartment 

Fuselage skin lap - 

stringers Nos. 19 

through 23 

Fuselage frames - 

cargo bin 

Fuselage - skin lap 

INSPECT 

FOR 

Corrosion 

Cracks/ 

Corrosion 

crushed 

frames 

Crushed 

fuselage 

frames/ 

cracks 

Corrosion 

Hfications 

COMMENTS 

(Ref: DSBs 

407 6( 858) 

Critical 

Area covered 

by ice plates 

(Ref: DSBs 

407 & 858) * 

Remove baggage bin 

floor and 

lining . 

None 

n to inspectil 

lay be found i 

INSPECTION 

TOOLS 

Visual 

X-ray 

Visual 

Visual 

Visual 

(Ref: DSBS 

407 bc 858) 

n of magnesium 

the manufact 

(l)*This condition is due to 

spillage from the 

lavatories. (NOTE 1) 

W*Close and frequent 

inspection should be 

made in this area. 

(1) Frequent inspections 

should be accomplished 

in this area. 

(1) None 

(1) Corrosion located in the 

faying surfaces of the 

skin lap approximately 

17" above the top of the 

first cabin window. 

(2) Popped rivets, paint 

blisters, pitted areas . F$ 

indicators. %X 3 

floor beams. 

rer's manual. 
FUSELAGE 

STATION 

F.S. 341 

F.S. 358 

to 391. 

F.S. 400 

to 417 

F.S. 400 

to 512 

DESCRIPTION 

Fuselage skin lap 

along stringer No. 26 

Fuselage skin, longeron frames . 

Fuselage skin 

Fuselage skin lap - 

stringer No. 19 . 

FUSELAGE STATIONS - DC-6/7 AIRCRAFT INSPECTIONS w* NU 

%s 3 

INSPECT COMMENTS INSPECTION REMARKS y 

FOR TOOLS 3c 

* 

Corrosion 

Corrosion/ 

Cracks 

Cracks/ 

Corrosion 

Corrosion 

None 

None 

Access throug 

wing fillet 

inspection 

plates. . 

Remove fillet 

for thorough 

inspection. 

(Ref: DSBs 

407 & 858‘) 

(Ref: DSBs 

407 & 858) 

Visual 

X-ray 

Visual. 

X-ray 

.Visual 

X-ray 

Visual 

X-ray 

(1) Severe corrosion 

located in the skin laps. 

(1) Corrosion located just 

belowthe cabin window. 

(2) Area should receive 

frequent attention. 

(1) Cracks lodated in skin 

above the front spar cap 

and along the fioor line. 

(2) Loose and popped rivets, 

paint and metal blisters 

are indicators of this 

condition. 

(1) Corrosion extended over 

a 2-inch wide strip 

along stringer No. 19. 

(2) Corrosion around and 

under the lower hinge 

fitting of the forward 

emergency exit at F.S. a+ 

448, iw 

*, 

.O 

al h) 
FUSELAGE STATIONS - DC-6/7 AIRCRAFT INSPECTIONS 

FUSELAGE 

STATION 

F.S. 500 

F.S. 448 

to 500 

F.S. 280 4 to 600 

DESCRIPTION 

Fuselage skin 

?uselage longitudinal 

skin lap 

Zabin floor structure 

and supports 

INSPECT 

FOR 

Cracks 

Cracks 

Cracks 

COMMENTS 

(Ref: DSB 

652) 

Inspect all 

exposed 

structure. 

Remove soundproofing as 

necessary for 

access to 

front and 

rear spars. 

(Ref: DSB 

4 dr 567) 

T INSPECTION 

TOOLS 

-~ 

Visual 

X-ray 

Dye Penetrant 

Visual 

Visual 

(1) Cracks are located in the 

fastener holes in the 

fuselage skin at the wing 

to fuselage attach angle. 

(2) Cracks also found in 

fuselage skin above rear 

spar. 

(1) Cracks located in the 

skin lap above the first 

and second cabin windows 

right side. 

(2) Crack le.ngth range up 

to 2” long. 

(1) Place particular emphasis 

on inspection of fuselage, 

frames 413, 421, 460, and 

5000 

(2) Ref. to DSB 567 for 

information concerning 

floor to frame bracket. w* Q,'d 

(3) Ref. DSB 611 and 651 for s 2 

inspection of attach "tee" a k 

fittings. x I * 
I FUSELAGE 

STATION 

I F.S. 280 

to 600 

F.S. 280 

to 600 

NOTE: Re er to the manufacture1 

DESCRIPTION 

Emergency exit 

cutouts 

Window frames 

FUSELAGE STATIONS - DC-6/7 AIRCRAFT INSPECTIONS 

INSPECT 

FOR 

Cracks 

Corrosion 

Is manual ar 

COMMENTS 

(Ref: DSBs 

407 & 858) 

i service bull 

INSPECTION 

TOOLS 

Visual 

Visual 

!tins for nece 

REMARKS 

(1) Cracks are located in 

the radius of the cutouts. 

(2) A service bulletin was 

issued covering this 

area, 

(3) Frequent attention 

should be given to this 

area. 

(1) Intergrannular corrosion 

located in the lower corner of No. 8 window. 

(2) Popped rivets, blisters 

in the skin, and paint 

are indicators. 

(3) Check . for presence of 

moisture in the insulation material. Ref. 

DSB 840, 

sary repairs. 
I 

. 

FUSELAGE 

STATION 

F.S. 280 

to 600 

F.S. 500 

to 600 

I 

F.S. 500 

9 to 600 

DESCRIPTION 

O”* 

FUSELAGE STATIONS - DC-6/7 AIRCRAFT INSPECTIONS ia *r\, 

NO m 4 \)ul 

Lavatory window 

Heater compartment, 

frames, longerons, 

floor beams 

Heater exhaust area 

longeron 24 

INSPECT 

FOR 

Corrosion 

Corrosion/ 

Cracks 

Cracks/ 

Exhaust 

damage 

CCMMENTS 

(Ref: DSBs 

407 6 858) 

If blankets 

are installed,check 

for moisture 

(Ref: DSB 

520) 

INSPECTION 

TOOLS 

Visual 

Visual 

Visual 

co REMARKS 

(1) Corrosion can found 

between the fuselage 

skin and doubler at the 

lower edge of the cutout. 

(2) Corrosion can become 

severe. Particular 

attention should be 

given to this area. 

(3) Evidence of moisture in 

the insulating material 

should be checked. 

(1) Cracks are located in 

the frames and longerons. 

(2) Moderate to severe 

corrosion in the floor 

beams. 

(1) Cracks and damage results 

from high heat exhaust 

temperatures. 

(2) Modifications have been w* g $ 

developed. m!3 wa )-' )I)* 

X 
_. . . 

FUSELAGE 

. 

STATION 

F.S. 500 

to 600 

F.S. 661 

to 1194 

F.S. 661 

to 1194 

1 

NOTE: Re 

FUSELAGE STATIONS - DC-6/7 AIRCRAFT INSPECTIONS 

DESCRIPTION 

Emergency exit doors 

Passenger entrance 

door frames, skin, 

floor, and buffet 

area 

Passenger entrance 

door hinge case 

er to the manufacture 

INSPECT 

FOR 

Cracks 

Cracks/ 

Corrosion 

Cracks/ 

Corrosion 

Is manual fc 

COMMENTS 

None 

(Ref: DSBs 

407 & 858) 

Removal of 

buffet 

required for 

thorough 

inspection 

(Ref: DSBs 

407 & 858) 

Y repairs and 

INSPECTION 

TOOLS 

Visual 

Visual 

Dye Penetral 

X-ray 

Visual 

Dye Penetrar 

lodifications 

(1) Cracks are located in 

the intercostal located 

immediately under the 

window. Cracks normally 

start in the angles. 

(1) Moderate to heavy 

corrosion in the door 

sill panel. 

(2) Corrosion in the buffet 

floor area can be severe. 

(3) Frequent and close 

inspection of these 

areas recommended. 

(1) Cracks are located at 

the front of the door 

frame, 

(2) Fuselage skin cracks at 

the upper forward corner 

of the door hinge cutouts 

and both upper and lower 

hinges. 
FUSELAGE STATIONS - DC-6/7 AIRCRAFT INSPECTIONS 

FUSELAGE 

STATION 

F.S. 661 

to 1194 

F.S. 661 

to 1194 

F.S. 10X 

to 1194 

F.S. 103c 

to 1194 

F.S. 103= 

to 1194 

DESCRIPTION 

Rear pressure bulkhead 

Tail cone area 

Horizontal stabilizer 

stub. (center section 

Tail cone area 

Horizontal stabilizer 

stub. (center sectior 

INSPECT 

FOR 

Cracks 

Corrosion 

Cracks 

Corrosion 

Cracks 

COMMENTS 

Chonic 

Light/Medium 

None 

Light/Medium 

None 

INSPECTION 

TOOLS 

Visual 

Dye Penetrant 

X-ray 

Visual 

Visual 

X-ray 

Visual 

Visual 

X-ray 

(1) Cracks are located in 

the stringers and attach 

fittings at the pressure 

bulkhead, 

(2) Frequent and close 

attention should be 

given to this area. 

(1) This can be controlled 

by cleaning treatment 

and painting. 

(2) Blisters and flaking of 

paint are indicators. 

(1) Cracks are located in 

the skin attach points 

to the front and rear 

spar. 

(1) This can be controlled 

by cleaning treatment 

and painting. 

(2) Blisters and flaking of 

paint are indicators. 

(1) Cracks are located in 

the skin attach points 

to the front and rear 

spar. 

P 
EMPENNAGE 

STATION 

Sta. 70 

to 130 

Sta. 30 

NOTE: XDESCRIPTION 

Horizontal stabilizer 

Horizontal stabilizer 

bay with steel bolts i 

rosion is difficult t 

. mtp P)d EMPENNAGE STATIONS - DC497 AIRCRAFT INSPECTIONS Yii! 3 rP1 

INSPECT CWMENTS INSPECTION REMARKS =P + x 

FOR TOOLS Fc 

Loose Visual (lI'Lo&e rivets located 

fasteners Dye Penetran in the lower skin where 

(numerous) Magnifying it is attached to the 

Cracks glass front spar. 

Cracked Cracks' are X-ray (1) Cracks are located in 

attach difficult the stabilizer attach 

fitting to locate. castings. 

Critical 

(2) Cracks usually start 

at the upper side of 

fitting which is covered 

by skin and progresses 

spanwise through the 

boltholes. . 

stalled wil result in blt Iking out def :ts in aluminum. 

detect by -ray if the pi rticles remai intact in the metal. 

=b Ar) 

L 

A0 

zcfn c\) 

(3) Particular attention 

should be given to 

these fittings since 

the cracks do not progress from the outside 

where they could be 

detected visually or 

with dye penetrant. 
EMPENNAGE 

STATION 

Sta. 126, 

202, and 

252 

Sta. 937 

to 1115 

Sta. 959 

to 986 

DESCRIPTION 

Elevators 

Rudder - torque tube 

Vertical stabilizers 

Vertical stabilizer 

EMPENNAGE STATIONS - DC-6/7 AIRCRAFT INSPECTIONS 

INSPECT COMMENTS INSPECTION 

FOR TOOLS 

Cracks None 

Wear/ None Visual (1) Excessive wear and 

Corrosion corrosion between the 

tube and the bearing 

seats. 

Cracks 

Cracks and (Ref:* DSBs Visual (1) Cracks have been found 

loose bolts 723 A796 and X-ray on the lower left side of 

in the 796) Dye Penetrant the vertical stabilizer. 

stabilizer RI* 

nose sectior DV 

(2) Particular attention op’d 

should be given to the (9 

ra 

metal cap after lightning cn s’ 

strike report for burned * 

areas l 

Visual 

(Ref: DSBs 723 Visual (1) Cracks are located in 

4796, and 796 X-ray the front fitting of the 

Dye Penetrant vertical stabilizer at 

the fuselage to vertical . 

stabilizer attach point. 

(1) Cracks located at the 

hinge cutouts on the 

elevator skin. 

(2) This can result in 

in-f light vibratiori due 

to looseness in the fits 

between the tube and 

bearing seats. 

I 

I 

WING 

STATION 

w.s.- 

0. -60 

KS. 

0-60 

W.S. 

O-60 

W.S. 

32 

KS. 

32 

, NOTE 1. 

DESCRIPTION 

Front upper spar csp 

Stringers, wing center section 

Center spar cap 

splices 

Front lower spar cap 

forward tang (extending thru fuselage) 

Front lower spar ceo 

aft tang (extending 

thru fuselage) 

* Cracks have develop 

operation due to ex 

w* 

WING STATIONS - DC-6/7 AIRCRAFT INSPECTIONS P 

INSPECT 

FOR 

Cracks 

Cracks 

Cracks 

Cracks 

Cracks 

d exceeding limitations rt 

cting fits, wing angle, ar 

COMMENTS 

(Ref. DSBs 

406 do 857) 

Internal 

inspection 

access door 

Internal 

inspection 

access door 

Internal 

inspection 

access door' 

Internal 

inspection 

access door 

Internal 

inspection 

access door 

INSPECTION 

TOOLS 

X-ray, 

Visual, 

Magnifying 

glass 

Dye Penetran 

X-ray, 

Visual, or 

Dye Penetran 

X-ray, 

Visual, or 

Dye Penetran 

Visual, 

Dye Penetran 

or X-ray 

Visual, 

Dye Penetran 

or. X-ray 

luiring spar 

1 disassembly 

REMARKS 

(1) Particular attention should 

be given this area. 

(2) -Crack length range up to 2" 

long. 

(1) Cracks found along forward 

side of stringer. 

(l)*Frequent and close attention 

should be given this area. 

(NOTE 1) 

(1) Routine inspection 

necessary. 

(1) Located at the bulkhead lap 

to tang 

(2) Particular attention should 

be given this area, 

eplacement. This is a complex 

required. 

z$ 

mtd 

a: 

ra 

ra 

x 

u 
WING 

STATION 

I W.S. 32 

W.S. 

32 

W.S. 

32 

W.S. 

55 - 60 

t KS. 

55 - 60 

NOTE: F 

DESCRIPTION 

Center lower spar cap 

forward tang (extending thru fuselage) 

Center lower spar cap 

aft (extending thru 

fuselage) 

Wing stringers 17 & 

26 at intersections 

with fuselage attach 

angles 

Center upper spar cap 

forward tang 

Center lower cap forward tang 

zfer to manufacturer r pair manual and service br 

-WING STATIONS - DC-6/7 AIRCRAFT INSPECTION WP D@d 09Q. 

9 

y 

COMMENTS LNSPECTION 

TOOLS REMARKS x 

ul 

INSPECT 

FOR 

Cracks 

Cracks 

Cracks 

Cracks 

Cracks 

None 

Internal 

inspection 

access door 

Internal 

inspection 

access door 

None 

Internal 

inspection 

access doors 

Visual, 

Dye Penetrant 

or X-ray 

Visual, 

Dye Penetrant 

or X-ray 

Visual or 

X-ray 

Visual or 

X-ray 

Visual or 

X-ray 

lletins for rt 

(1) Routine inspection ' 

necessary. 

(1) Located at bulkhead lap 

to tang. 

(2) This area should receive 

frequent attention. 

(1) Cracks found along forward side of stringer. 

(2) Cracks located in forward line of rivets in 

spar 'cap. 

(1) Cracks located inboard 

of attach angles. 

(2) Place particular emphasis 

on this area. 

(1) Cracks located in tang at 

skin lap. 

(2) This area should be 

frequently inspected. 

lair instructions. 
WING STATIONS - DC-6/7 AIRCRAFT INSPECTIONS 

WING 

STATION 

W.S. 

55-60 

W.S. 

55-60 

W.S. 

60 

KS. 

60 

W.S. 

60 

NOTE: 

DESCRIPTION 

Center upper spar 

cap aft tang 

Center lower spar 

cap aft tang 

Inboard end of flap 

top nose section 

skin 

Nos. 2 & 3 fuel tank 

access doors 

Upper wing to fuselage attach angles 

efer to manufacturer 

INSPECT 

FOR 

Cracks 

Cracks 

Cracks 

Cracks Outside surand popped face inspecrivets tion 

Cracks Internal 

inspection 

access door 

epair manua 

CQ9MENTS 

None 

None 

Outside surface inspection 

and service 

INSPECTION 

TOOLS 

Visual or 

X-ray 

Visual or 

X-ray 

Visual, 

Magnifying 

glass 

Visual, 

Magnifying 

glass 

Visual, 

Dye Penetrant, X-ray 

Jlletins for 

REMARKS 

(1) Cracks located inboard of 

attach angle. 

(2) Place special emphasis on 

inspection of cap at 

longeron 22. ' 

(1) Cracks located in tang at 

skin lap. 

(2) Particular attention should 

be given this area. 

(1) Cracks located along rivet 

lines and difficult to 

locate. 

(1) Crack location - radius 

of cutouts and skin. 

(2) Routine inspection necessary. 

(1) Crack location - cracks in 

boltholes, 

(2) Frequent inspections should F$ 

be accomplished in this area.% z 3 

e'pair instructions. WE 

X 

u 
WING 

STATION 

W.S. 

60 

WA. 

60 -65 

KS. 

60 -65 

W.S. 

67 

W.S. 

67 

DESCRIPTION 

Front lower spar cap 

aft tang boltholes 

Front lower spar cap 

aft tang 

Front lower spar cap 

forward tang 

Wing stringer 22 

inboard and outboard 

of this station 

Wing stringer 23 

inboard and outboard 

of this station 

WING STATIONS - DC-6/7 AIRCRAFT INSPECTIONS w* @cd uQ)b 

'ps 

COMMENTS REMARKS *rp: $4 INSPECT 

FOR 

INSPECTION 

TOOM 

Cracks 

Cracks 

Cracks 

Cracks 

Cracks 

Internal 

inspection 

access door 

Internal 

inspection 

access doors 

Internal 

inspection 

access doors 

Internal 

inspection 

access doors 

Internal 

inspection 

access doors 

VisuaLor 

X-ray 

Visual or 

X-ray 

Visual or 

X-ray 

Visual or 

X-ray 

Visual or 

X-ray 

. 

(1) Crack location - 

horizontally between tang . 

and spar cap. 

(2) DSBs A678, 678, and 694 

aPPlYi 

(1) Cracks located at skin lap 

in tang. 

(2) Routine inspection 

necessary. 

(1) Cracks located horizontally 

between tang and. spar cap. 

(2) Frequent inspection 

should be made of this 

area. 

(1) Cracks located 'forward 

row of rivets. 

(2) Close and frequent 

inspection necessary. 

(1) Cracks start in forward 

row of rivets. Qcb lc3 

(2) DSB issued on this area. Ao Ph) 

%k N 
! 

I WING 

STATION 

KS. 

60 

W.S. 

60 

130. 

W.S. 

96 

KS. 

77 - 96 

W.S. 

i 133 - 

163 

a>+ WING STATIONS - DC-6/7 AIRCRAFT INSPECTIONS \n fu 

DESCRIPTION 

Stringers at splices 

on lower wing plate 

Stringers 17, 18, 19, 

20, and 21 

Stringers 18, 19, 

and 20 

Center spar web' 

inside wing fuel cell 

cavity 

Upper and lower spar 

caps in corner of 

nacelle spar area 

INSPECT 

FOR 

Cracks 

Cracks 

Fatigue 

Cracks 

Cracks 

(Some . 

cases 5" 

to 6" 

long) 

Cracks 

(fuel 

stains are 

telltale 

signs) 

COMMENTS 

Internal 

inspection 

access doors 

(Ref: DSBs 

406 & 857) 

Internal 

inspection 

access door 

(Ref: DSBs 

406 & 857) 

Access 

between landing gear, 

drag strut, 

and main gear 

strut 

INSPECTION 

TOOLS 

Visual or 

X-ray 

Visual or 

X-ray 

Visual 

X-ray 

Visual 

Magnifying 

glass 

Dye Penetranl 

Visual 

Dye Penetrati 

X-ray 

REMARKS xl ?a 

(1) Refer to DSB 561. 

(2) Cracks start in forward 

row of rivets. ' 

(1) Cracks have been found in 

both forward and rear rivet 

holes. 

(2) Particular attention 

should be given this area. 

(1) Crack location - forward 

row of rivets. 

(2) Reference DSB 561. 

(1) Cracks located vertically 

along web stiffener. 

(2) Full cell liners must be 

removed for access to this 

area. 

(1) Cracks radiate horizontally Fg 

from rivet holes. m'b 

Y ma (2) Particular attention should 5;' 

be given this area. cn 
1 WING 

STATION 

I 

W.S. 

130 - 

167 

W.S. 

122 

W.S. 

171 

W.S. 

114.5 

W.S. t 

148 

NOTE: R 

DESCRIPTION 

Top wing skin under 

nacelle fairing wing 

Center lower spar cap 

aft tang at three 

boltholes 

Center lower spar cap 

aft tang 'at three 

boltholes 

Center lower spar cap 

and wing skin from 

inboard side of No. 2 

nacelle inboard to 

this W.S. 

Center lower spar cap 

and wing skin from 

outboard side of NO, : 

nacelle outboard to 

this W.S. 

!fer to manufacturer% manua 1 and 

WING STATIONS - D&6/7 AIRCRAFT INSPECTIONS 

INSPECT 

FOR 

Corrosion/ 

Cracks 

Cracks 

Cracks 

Cracks 

Cracks 

COMMENTS 

Area susceptible to 

engine 

exhaust, 

gases, and 

vibration 

(Ref: DSBs 

406 & 857) 

Internal 

inspection 

access door 

Internal 

inspection 

access door 

Internal 

inspection 

access door 

Internal 

inspection 

access door 

2rvice bullet: 

INSPECTION 

TOOLS 

Visual 

Visual or 

X-ray 

Visual or 

X-ray 

Visual or 

X-ray 

Visual or 

X-ray 

1s for crack 1 

- 

REMARKS 

(1) Reference DSB 762. 

(2) This can be controlled by 

cleaning treatment and 

painting. 

(3) Blisters and flakes of 

paint are indicators.. 

(1) Cracks radiate from boltholes. 

(2) Routine inspection 

necessary. 

(1) Cracks radiate 

horizontally, length of 

crack up to 3". 

(1) Crack location - forward 

line of rivets. 

(1) Crack location - forward 

and aft row of rivets. 

(2) Cracks found in skin 

under spar. 

2pair and corrosion treatment. 
WING 

STATIO! 

W.S. 

114.5 

KS. 

148 

W.S. 

131 

NOTE: 

DESCRIPTION 

Center lower spar car 

and wing skin from 

inboard side of No. 3 

nacelle inboard to 

this W.S. 

Center lower spar 

caps and wing skin 

from outboard side of 

No. 3 nacelle outboard of this W.S. 

Nos. 2 and 3 nacelle 

lower wing skin 

inboard of W.S. 167 

outboard W.S. 131 

.efer to manufacturer* 

reatment. 

WING STATIONS - D&6/7 AIRCRAFT INSPECTIONS rn* '0 ra 

INSPECT 

FOR 

Cracks 

Cracks 

Cracks/ 

Corrosion 

I manual and service bulle ins for crack repair and corrosion 

- 

COMMENTS 

Internal 

inspection 

access door 

Internal 

inspection 

access door 

Internal 

inspection 

access door 

*N 

>O 

INSPECTION 

TOOLS . 

Visual or 

X-ray 

Visual or 

X-ray 

Visual or 

X-ray 

REMARKS Zen h) 

(1) Crack length varies up to 

. 2" - 3 II l 

(2) Usually located on front 

line of rivets. 

(1) Crack location - forward 

and aft line of rivets. 

(2) Routine inspection 

necessary. 

(1) Moderate to severe 

corrosion. 

(2) Cracks radiating from 

rivet holes., 

. 
WING 

STATION 

W.S. 

131 

KS. 

131 

I W.S. 

167 - 

282 

NOTE: R 

DESCRIPTION 

Splice or tie plates, 

landing gear, spar 

cap, lower front 

Center wing lower 

skin aft of center 

spar 

Aft and of main landing gear door 

assemblies 

Lower wing skin 

!fer to manufacturer% 

u* 

WING STATIONS - DC-b/7 AIRCRAFT INSPECTIONS P'd CJQTJ 

vi 

ma 

COMMENTS REMARKS P* 94 INSPECT 

FOR 

INSPECTION 

TOOLS 

Cracks 

Cracks and 

Corrosion 

Cracks and 

Corrosion 

Small 

cracks and 

corrosion 

manual for : 

Access thru 

wheel well 

Outside surface inspection 

Outside 

surface 

inspection 

(Ref: DSBs 

406 & 857) 

tin repair ant 

Visual, 

Dye Penetrant 

X-ray 

Visual or 

X-ray 

Visual or 

X-ray 

Visual or 

X-ray 

corrosion 

. 

trc 

(1) Cracks located 

horizontally in lower 

cap where plates attach, 

(2) Routine inspection 

necessary. 

(1) Moderate to heavy 

corrosion. 

(2) Frequent and close 

inspection of this area 

recommended. 

(1) Moderate to light 

corrosion. 

(2) Cracks radiating from 

aft row of rivets. 

(1) Corrosion can become 

severe. 

(2) Frequently inspect this 

area. r 

itment. ' 
WING 

STATION 

W.S. 

183 

W.S. 

203 - 

282 

W.S. 

281 

W.S. 

281 

KS, 

242 

NOTE: 

DESCRIPTION 

Leading edge rib 

Stringers caps and 

crowns 

Wing skin and large 

fasteners 

Stringer tie ends 

Stringer No. 23 

inboard/outboard of 

W.S. 

,efer to manufacturer' 

.reatment. 

DC-6/7 AIRCRAFT INSPECTIONS oo* 

WING STATIONS - AC3 

L 10 

INSPECT 

FOR 

COMMENTS INSPECTION 

TOOLS 

REMARKS xl N 

Cracks 

Cracks 

inside and 

out, loose 

rivet 

Cracks 

Corrosion 

Cracks and 

loose 

rivets 

manual and 

(Ref: DSBs 

406 & 857) 

None 

Outside 

surface 

inspection 

Access door 

Internal 

inspection 

access door 

ervice bullet ns for crack 

Visual or 

X-ray 

X-ray 

Visual 

Visual 

Visual or 

X-ray 

(1) Routine inspection of 

this area. 

(1) Cracks located in 

fastener holes. 

(2) Crack length up to 

2" long. 

(1) Cracks located parallel 

to ribs. - 

(2) Crack length up to 4" 

long. 

(1) Moderate to heavy 

corrosion. 

(2) Frequent inspections 

of this area. 

(1) Particular attention 

should be given this 

area. 

epair and corrosion 

3 \oa P* 

x 

cn 
m* 

WING STATIONS - DC-6/7 AIRCRAFT INSPECTIONS P'd cm@73 

*!t 

WING 

STATION 

KS. 

242 

KS. 

130 - 

167 

300 - 

336 

W.S. 

318 

W.S. 

1.49 - 

318 

W.S. 

318 

NOTE: 

T 

Rc 

t: 

DESCRIPTION 

Leading edge access 

door plate hinge, aft 

tang 

Frame of nacelle 

where attached to 

skin 

Wing skin behind outboard nacelle 

Wing skin under 

nacelle turtle back 

Supercharger mount 

, 

frames 

fer to manufacturer's 

eatment. 

INSPECT 

FOR 

Corrosion . 

and wear 

Cracks 

Corrosion 

(small 

pits) 

Cracks 

Cracks 

nanual and 1 

COMMENTS 

Internal 

inspection 

access door 

Access thru 

inspection 

opening on 

nacelles 

Outside 

surface 

inspection 

Nacelle must 

be removed 

to locate 

cracks 

Access thru 

inspection 

door 

xvice bulleti rs for crack r 

INSPECTION 

TOOLS 

Visual or 

X-ray 

Visual 

Visual 

X-ray 

Visual 

(1) Corrosion is moderate to 

severe. 

(2) Frequent cleaning treatment necessary. 

(1) Nuisance cracks. . 

(2) Routine inspection 

necessary. 

(1) Corrosion is severe. 

(2) Frequent cleaning is 

necessary. 

(1) Cracks vary in length 

up to 2". 

(2) Particular attention 

should be given this 

area. 

(1) Transverse cracks have 

been reported. 

(2) This area should be 00s 

given frequent inspections. Z0 *IQ 

-3 

pair and corrosion %!n N 
I WING 

STATION 

WA 

281 

KS, 

. 281 

W.S. 

281 

KS. . 

281 

1 

KS. 

293 

NOTE: .efer to Douglas Service 

DESCRIPTION 

Fuel tank sealants 

Wing skin 

Upper spar rail 

"Tee" angles 

Stringer No. 22 aft of 

center spar inboard/ 

outboard of KS. 

. 

00 

WING STATIONS - DC-6/7 AIRCRAFT INSPECTIONS \* NO Fc -h) 

m0 

COMMENTS REMARKS -1 u h) INSPECT 

FOR 

INSPECTION 

TOOLS 

Corrosion 

Cracks ant 

fuel leaks 

Corrosion 

Cracks 

Cracks ant 

loose 

rivets 

Bulletini 

Access door 

Outside 

surface 

inspection 

Access thru 

landing gear 

well 

Internal 

inspection 

access door 

Internal 

inspection 

access door 

Nos. 406 and 

Visual 

Visual or 

X-ray 

Visual or 

X-ray 

Visual or 

X-ray 

Visual or 

X-ray 

157 for additi 

(1) Corrosion found on wing 

skin when sealants removed. 

(2) Frequent inspections of 

this area. 

(1) Particular attention should 

be given this area. Consult 

manufacturer if repair not 

in repair manual. 

(1) Corrosion light to moderate. 

(2) Area should receive 

frequent attention. 

(1) None 

(1) Cracks are usually in forward line of rivets. 

(2) Routine inspections 

necessary. 

lnal information. 
WING STATIONS - DC-617 AIRCRAFT INSPECTIONS 

WING 

STATION 

W.S. 

293 

W.S. 

242 

KS. 

300 - 

336 

W.S. 

149 - 

318 

W.S. 

149 

NOTE: 

DESCRIPTION 

Stringer No. 23 aft 

of center spar 

inboard/outboard of 

KS. 

Stringer No. 22 

inboard/outboard of 

W.S. 

Nacelle former flange 

'(nacelle station 414) 

Nacelle to center 

spar attach gussets 

(nacelle station 460) 

Front spar cap forward lower tang at 

No. 3 inboard and 

outboard nacelle 

attach angle boltholes 

:er to manufacturer's m 

INSPECT 

FOR 

Cracks and 

loose 

rivets 

Cracks and 

'loose 

rivets 

Cracks 

Cracks 

Cracks 

nual and se 

COMMENTS 

Internal 

inspection 

access door 

Internal 

inspection 

access door 

Access thru 

inspection 

plate 

Access thru 

inspection 

plate 

Access thru 

landing gear 

wheel well 

vice bulletin 

INSPECTION 

TOOLS 

Visual or 

X-ray 

Visual or 

X-ray 

Visual 

Visual 

Visual or 

X-ray 

for repair i 

(1) Crack location - on both 

forward and aft row of 

rivets. 

(2) Check for loose rivets. 

(1) Crack location - aft row 

of rivets. 

(2) Length of cracks reported 

up to 2". 

(1) Crack location - parallel 

to former. Area should 

receive close attention. 

11) Cracks start in gussets 

and parallel to spar cap. 

(2) Routine inspections 

necessary. 

11) Cracks in tang found up 

to 4” long. 

;tructions. 
WING 

STATION 

W.S. 

318 

W.S. 

302 - 

312 

W.S. Fasteners inboard of 

336 outboard nacelles 

4 

W.S. 

339 

NOTE: 

DESCRIPTION 

Front spar cap forward lower tang at 

No. 4 inboard and 

outboard nacelle 

attach angle bolts 

Center lower spar 

cap forward tang at 

fuel sump cutout 

radius in cap inboar 

(W.S. 302) and outboard (W.S. 312) end 

of numbers 1 and 4 

alternate tank sumps 

(bolts removed) 

Center spar upper 

rai 1 

3fer to manufacturer' 

WING STATIONS - DC-6,7 AIRCRAFT INSPECTIONS oo* \n 

INSPECT 

FOR 

Cracks 

Cracks 

Cracks 

Cracks 

repair manu 

COMMENTS 

Access thru 

landing gear 

wheel well 

Access thru 

landing gear 

wheel well 

Outside surface inspection 

Access thru 

main landing 

gear whee 1 

well 

.l and service 

INSPECTION 

TOOLS 

Visual or 

X-ray 

Visual or 

X-ray 

Visual 

Visual 

X-ray 

bulletins for 

(1) Cracks in tang radiate 

from rivet line. 

(1) Cracks are located in 

fastener holes and also 

in wing skin. 

(2) Crack length ranges up 

to. 2" long. 

(1) Cracks radiate from 

fastener holes parallel 

to ribs. 

(1) Cracks are located in 

the skin attach points. 

(2) Routine inspection is 

necessary. 

repair instructions. 
WING STATIONS - DC-6/7 AIRCRAFT INSPECTLONS 

WING 

STATION 

KS. 

421 

W.S. 

336 

W.S. 

336 

W.S. 

378 

W.S. 

378 

NOcrE: F 

DESCRIPTION 

Stringer No. 26 hat 

sections and attach 

fittings 

Wing stringer No. 22 

(outboard of this 

station) 

Wing stringer No. 23 

(outboard of this 

station) 

Wing stringer No. 22 

(inboard and outboard 

of this station) 

Wing stringer No. 23 

(inboard and outboard 

of this station) 

zfer to manufacturer's 

INSPECT 

FOR 

Cracks/ 

Corrosion 

Cracks/ 

Corrosion 

Cracks/ 

Corrosion 

Cracks/ 

Corrosion 

Cracks/ 

Corrosion 

repair manu 

COMMENTS 

Access thru 

inspection 

door 

Access thru 

inspection 

door 

Access thru 

inspection 

door 

Access thru 

inspection 

door 

Access thru 

inspection 

door 

1 and service bulletins for 

INSPECTION 

TOOLS 

Visual (1) Corrosion moderate to 

X-ray heavy. 

Visual 

X-ray 

Visual 

X-ray 

Visual 

X-ray 

Visual 

X-ray ' 

(2) Cleaning and painting 

will control. 

(1) Corrosion moderate to 

heavy. 

(2) Area should be frequently 

inspected. 

(1) Corrosion moderate. 

(2) Cracks parallel stringer 

longitudinally. 

(1) Corrosion moderate. 

(2) Cracks range up to 3" 

long. 

(1) Corrosion light to 

moderate. 

(2) Frequent inspections 

necessary. 

repair information. 

. 
. WING 

STATION 

KS. 

399 

W.S. 

399 

W.S. 

421 

W.S. 

421 

W.S. 

435 - 

453 

NOTE: 

WING STATIONS - DC-6/7 AIRCRAFT INSPECTIONS e* NC, 

DESCRIPTION 

Wing stringer NO. 22 

(inboard and outboard 

of this station) 

Wing stringer No. 23 

(inboard and outboard 

of this station) 

Inboard end of wing 

and lower and of 

attach fittings and 

stringers 

ltTee" clips at end 

of spars 

Upper wing skin at 

skin lap at front 

spar 

tefer to manufacturer's 

INSPECT 

FOR 

Cracks/ 

Corrosion 

Cracks/ 

Corrosion 

Corrosion 

Cracks 

Cracks 

repair manu 

C@MENTS 

Access thru 

inspection 

door 

Access thru 

inspection 

door 

Internal 

inspection 

access door 

None 

Outside 

surface 

inspection 

1 and service 

. 

INSPECTION 

TOOLS 

Visual 

X-ray 

X-ray 

Visual 

Visual 

X-ray 

Visual 

xMetins for 

(1) Severe corrosion reported. 

(2) Cracks are longitudinal, 

crack length up to 3" 

long. 

(1) Corrosion moderate to 

heavy. 

(2) Cracks involve stress 

corrosion. 

(1) Corrosion light to 

moderate, 

(2) Sealant area must be 

inspected. 

(1) None 

(1) Cracks parallel rivet 

row@ 

(2) Routine inspection is 

necessary. 

repair information. 
WING 

STATION 

W.S. 

421 - 

710 

KS. 

421 - 

705 

KS. 

462 - 

517 

KS. 

485 

W.S. 

60 - 

710 

NOTE: 

i NOTE 1. * Fiber glass trailin! 

DESCRIPTION 

Rib clips (90') 

Aileron well 

Aileron trim. tab 

hinge points 

Aileron bell crank 

Wing trailing edge 

skin, ribs, clips, 

and stringers 

efer to manufacturer'; 

nformation. 

WP 

. WING STATIONS - DC-6/7 AIRCRAFT INSPECTIONS Pm 

YKii 3 I l-a 

REMARKS m r* INSPECT x 

FOR 

COMMENTS INSPECTION 

TOOLS cn 

Cracks 

Small 

cracks 

Small 

cracks 

Cracks 

Nuisance 

cracks 

manuals ant 

edge will c 

Internal 

inspection 

access door 

Outside 

surface 

inspection 

Outside 

surface 

inspection 

Internal 

inspection 

access door 

Internal 

inspection 

and also on 

outside surface (Ref: 

DSBs 406 6s 

857) 

service bulle :ins tor repai 

!velop small c l acks in radiu 

Visual 

Visual 

Visual 

Visual 

Visual 

(1) Cracks radiate from 

fastener holes on 

stringer and/or rib., 

(1) Routine inspection of 

this area. 

(1) Particular attention . 

should be given this 

area, 

(l)*Failure have been 

reported due to wing 

gust loads on ground. 

(See Note 1) 

(1) These areas should 

receive frequent 

inspections. 

and corrosion treatment 

oob 

at tip. (Maintenance item) \c3 

L 10 

m I NJW rQ 
WING 

STATION 

KS. 

60 - 

470 

KS. 

167 

281 

334 

Wing flap links 

W.S. Wing flap support aft 

167 boltholes 

W.S. 

281 Spacer block/flap 

actuator 

NOTE 1. 

DESCRIPTION 

Wing trailing edge 

and flap well area 

* Misalignment of linl 

impose large loads ( 

in cracking in this 

WING STATIONS - DC-6/7 AIRCRAFT INSPECTIONS 

O”P 

iv 

INSPECT 

FOR 

Corrosion 

Cracks and 

Misalignment 

Oversize 

hole 

Improper 

clearance 

s will resu: 

n brackets 1 

5rea. 

COMMENTS 

Outside 

surface 

inspection 

Outside 

surface 

inspection 

Service wear 

None Visual (1) None 

: in cracking 

lat are attach 

INSPECTION 

TOOLS 

Visual 

Visual 

Visual 

:he link and a 

!d to the rear 

RIPlARKS rlul h> 

(1) Corrosion moderate to 

heavy due to exhaust gases. 

(2) Frequent and close 

inspection of these areas 

recommended. 

(3) Frequent cleaning and 

treatment necessary. 

(l)*Routine inspection of this 

area desirable. (See 

Note 1) 

(1) Routine inspection of 

this area. 

tach brackets. Also, it will Fg 

spar structure which can result % x 

3 PCL \J b-J* 94 
WING 

STATIONS 

W.S. 

63 

421. 

W.S. 

63 

421- 

NOTE: Rc 

WING STATIONS - DC-6/7 AIRCRAFT INSPECTIONS 

DESCRIPTION 

Flap trailing edges 

Flap structure damage 

fer to manufacturer% 

INSPECT 

FOR 

Warpage 

Cracked 

ribs, clip 

skin, and 

loose 

rivets 

repair manua 

CCMMENTS 

Outside 

surface 

inspection 

None 

. and service 

INSPECTION 

TOOLS 

Visual 

Visual 

julletins for 

REMARKS 

(1) Excessive warpage may 

cause flight control 

problem, 

(2) Particular attention 

s,hould be given this 

area. 

(1) Damage is usually 

caused during ground 

operation. 

(2) This area should receive 

frequent inspections. 

etailed repair instructions. 
AC 20-52 Appendix 6 

8/24/67 Page 1 

APPENDIX 6. 

1 . DC-6 AIRCRAFT MAINTENANCE INFORMATION. The following is a listing 

of significant maintenance difficulties that have been reported by 

air carriers as mechanical reliability reports from 1964 to 1967. 

This information may be useful in identifying additional structural 

inspection areas: 

a. Wings. 

(1) During an overhaul inspection, the main landing gear outer 

cylinder, P/N 8065H2, was found cracked in the radius area 

of the outside diameter of the cylinder just below the "YO 

arms. Repairs . were accomplished in accordance with the 

manufacturer+ instructions. The- aircraft total time was 

25,000 flight hours. This same condition was found on 

another aircraft having 31,000 flight hours. # 

(2) Cracks were found in the trunnionbore of the left and right 

front spar main landing gear drag strut fitting. The drag 

strut fitting was replaced. The aircraft total time was 

49,786 flight hours. 

(3) During inspection, the right wing flap strut assembly link 

support, P/N 5329694, located at W.S. 167 was found cracked 

at the aft end. The flap support was replaced. Time since 

the last inspection was 509 hours. 

(4) During landing, the left wing flap was damaged. Investigation 

revealed that the left outboard hinge bracket assembly, P/N 

3365189, was broken. The bracket was replaced. 

(5) A two-inch crack was found in the upper wing skin. The crack 

was located at W.S. 96, inboard of the No. 3 nacelle in 

the aft corner of the tank access hole. The aircraft total 

time was 25,208 hours. . 

(6) During inspection, the right and left flap hinge fittings 

were found cracked in the inboard web at the radius of the 

hinge hanger cutout at W.S. 167. Hinge fittings, P/N 54922130 

13 and -14 were replaced. Aircraft total time was 19,783 

hours. 

(7) During a basic service check, the left front spar drag 

fitting, P/N 5325648, was found to be cracked. The crack 

ran from the drag strut fitting cutout, inboard and parallel 

with the front spar, approximately two and one-half inches 

below the inboard lug. The crack was approximately three 

inches long. The total time on the aircraft was 30,609 

flight hours. The manufacturer has issued rework instructions 

including repetitive inspections at 100-hour intervals. 
Appendix 6 

Page 2 

(8) A one-inch crack in the lower skin of the right wing was found 

during a periodic inspection. The crack was located at W.S. 185 

and 16 inches behind the center spar. Total flight time on the 

aircraft was 45,987 flight hours. A repair can be found in the 

manufacturer% repair manual. 

' (9) A one-inch chordwise crack was found in the upper inboard attach 

angle of number one nacelle where it is attached to the front 

tang of the center spar. Also, a one-inch crack was found in 

this same angle where it attaches to the aft tang of the center 

spar. Approved repairs were accomplished. The aircraft total 

time was 23,749 flight hours. 

(10) During a block overhaul, the upper left wing skin was found to 

be cracked at station 130. The crack was located forward of 

the center spar tangs. The crack ran diagonally and was two 

inches long. No other discrepancies were noted in the sur- . 

rounding structure. 

(11) Two chordwise cracks were found in the right wing lower skin 

at the stringer and fittings located at station 281. Manufacturer has a service bulletin covering the repair in this 

area. The total time on the aircraft was 18,214 flight hours. 

(12) A two-inch crack was detected during a visual inspection in the 

box beam. The crack was located in the lower side of the right 

center forward and of the box beam in the aft cargo compartment. 

The repair for this area can be found in the manufacturer% 

structural repair manual. The total time on the aircraft was 

47,045 flight hours. 

(13) A crack was found in the inboard attach angle at the center 

spar bolt in No. 4 engine nacelle. This was repaired in 

accordance with the manufacturer's repair manual. 

(14) During a visual and dye penetrant inspection, a one-half inch 

crack was found in the gyro-support bracket. The crack extended 

from the bracket hole to the edge of the spar at the forward 

tang of the lower front spar cap at station 4. A repair was 

made in accordance with the manufacturer's structural repair 

manual. The total time on the aircraft was 44,155 flight hours. 

(15) Stringer No. 18, located at station 300, was found to be 

cracked. The repair was made in accordance with manufacturer% 

Service Bulletin No. 561. The total time on the aircraft was 

23,725 flight hours. 
AC 20-52 

8/24/67 

Appendix 6 

Page 3 

(16) A three-inch crack was found in the attach angle at the 

point where the wing is joined to the fuselage aft of 

the front spar. The repair was accomplished in accordance 

with an approved repair. The total time on the aircraft 

was 23,725 flight hours. 

(17) During a basic service inspection, the bottom tang of the 

left wing front spar was found cracked at station 160. 

, The repair was accomplished in accordance with the manufacturer's service bulletin. 

(18) A crack was found in the wing attach angle doubler where 

the wing joins the fuselage at station 400. A repair can 

be found for this area in the manufacturer+ repair manual. 

(19) During overhaul, spanwise stringer No. 23 on the lower 

wing surface was found cracked. The crack ran chordwise ' 

in the stringer crown and was located at W. S. 325. 

The repair was accomplished in accordance with an approved 

repair method. Total time on the aircraft was 18,164 

flight hours. 

(20) The right wing lower skin was found to be cracked between 

the front and rear spars at W.S. 281, This repair was 

made in accordance with an approved repair method. Total 

time on the aircraft was 23,725 flight hours. 

(21) Cracks were found in the left wing fuel tank access plate 

doublers 182b and 182~. Manufacturer's Service Bulletin 

No. 799 covers the repair of this area. Total time on 

the aircraft was 23,752 flight hours. 

(22) During overhaul, the right-hand splice angle, P/N 42435221, 

on the nosewheel beam forward pressure bulkhead Gas broken, 

The attach angle was replaced with a new part. Total time 

on aircraft was 51,368 flight hours. 

(23) The right center spar tang was found cracked at the bolthole outboard of the fuselage skin. Also, the attach 

angle was cracked at the same bolthole. This crack was 

approximately one inch in length. Manufacturer's Service 

Bulletin No. 678 covers the repair of this area. Total 

time on the aircraft was 48,958 flight hours. 

(24, A four-inch crack was detected, by visual inspection, in the 

radius of the bottom vertical angle of the front spar at 

station @'O*'. The angle was replaced. Also, a two-inch 

crack was found in the front spar on the left side of the 

conduit hole located at station 28. A doubler was installed. 

Total time on the aircraft was 47,112 flight hours. 
AC 20-52 

8124167 

(25) A visual inspection revealed that the upper wing skin was 

heavily corroded in the area just forward of the rear spar 

at station 167. The section of wing skin was replaced. 

Total time on the aircraft was 45,73? flight hours. 

(26) During inspection, corrosion was noted on the doubler of 

the left wing trailing edge between stations 300 and 357. 

A section of wing skin was removed that was 37 l/2 inches 

long and 10 3/4 inches wide. A repair for this area can 

be found in the manufacturer% repair manual. 

(27) Inspection of the center lower spar cap revealed a crack 

that progressed fore and aft through the cap and upwards 

into the spar web approximately three inches. The crack 

was located in the left wing at W.S. 170 under the NO. 2 

outboard lower fairing. Aircraft total time was 37,386 

flight hours. 

(28) During aircraft overhaul, the right main loading gear drag 

strut to the front spar fitting, P/N 5325648, was found. 

cracked. The crack was located in the inboard brushing 

bore adjacent to the bore for the large trunnion nut. 

Aircraft total time was 52,263 flight hours. 

b a Fuselage. 

(1) 

(2) 

(3) 

(4) 

Inspection of the fuselage during a block overhaul revealed 

that the skin was cracked at the emergency exit cutout on 

the right side of the fuselage at station 557. The operator 

established an inspection of this area in its maintenance 

program to preclude further cracks. The total time on the 

aircraft was 23,749 flight hours. 

During a block overhaul, the left ice plate was removed from 

F.S. 260. A one and one-half inch crack was found that 

was progressing vertically between stringers Nos. 21 and 22. 

Also, a one-ix-&crack was progressing horizontally between 

stringers Nos. 22 and 23. The total time on the aircraft 

was 23,749 flight hours. 

During a service inspection, cracks were found in the 

frame to foot fittings doubler at stations 497.5 and 498.5. 

The repairs were accomplished in accordance with the manufacturer's recommendations. 

The fuselage circumferential flange to the left stringer 

NO. 24 was found cracked at station 238L. The affected 

part of the flange was replaced. 

-- 
AC 20-52 

8/24/67 

(5) 

(6) 

(7) 

(8) 

Appendix 6 

Page 5 

Corrosion was found around cabin windows 2, 3, 5, 7, 

8, 9, and 10 on the left side of the fuselage and 4, 

7, and 10 on the right side. The areas were cleaned, 

treated, and the metal replaced as required. 

During overhaul, the upper fuselage attach angle was 

found cracked. Repairs were accomplished in accordance 

with the manufacturer% manual. 

During an airworthiness directive compliance inspection, 

a transverse crack was found in the frame at F.S; 95. 

The crack was located just above longeron No. 10. Repairs 

were made in accordance with the manufacturer's instructions. 

Aircraft total time was 27,341 flight hours. 

During overhaul, the wing skin to fuselage from attachment channel, P/N 5503731-l and -2, was found cracked. 

The crack is located at F.S. 413 on the left side and ' 

it progressed through the upper inboard horizontal 

flange and vertical leg of the channel. The channels 

were replaced. Aircraft total time was 30,143 flight hours. 

c. Stabilizers. 

(1) During a periodic inspection, a fitting, P/N 4801674, 

was found cracked. The fitting is located on the right 

stabilizer at station 60. The combined length of the 

five short cracks was 6 l/8 inches. The fitting was 

replaced and continued inspection of this area is 

planned. The total time on the aircraft was 37,287 

flight hours. 

(2) During a periodic inspection, the right horizontal 

stabilizer attach fitting, P/N 4361674-1, was found to 

be cracked. This fitting is located at station 63 

forward and on the top of the front spar. The fitting 

was replaced and inspection of this area will be continued at the periodic inspection period. The total 

time on the aircraft was 45,759 flight hours. 

(3) The left horizontal stabilizer spar lower forward outboard fitting was found cracked. The fitting was 

replaced. Total time on the aircraft was 46,369 flight 

hours. 

(4) During a service inspection, corrosion was found on the 

aft leg of the rear spar attach fitting, P/N 5361821, at 

the vertical stabilizer stub. The fitting was replaced. 

Aircraft total time was 35, 071 flight hours. 
Appendix 6 AC 200 52 

Page 6 8124167 

d. . Flight Controls. 

(1) A ten-inch tear was found in the right-hand wing flap during 

a service ,check. This tear was located at station 415 and 

the tear was from inside out. The fairing at this station 

also had 10 rivets pulled loose. A repair was made in 

accordance with the operator% structural manual. Total 

time on the aircraft was 46,597 flight hours. 

(2) A visual inspection revealed a cracked flap support, 

P/N 5329659. This was a complete.failure of the part. The 

location of the part is at the right W.S. 167. The flap 

support assembly was replaced. The total time on the aircraft was 47,418 flight hours. 

(3) The right-hand flap hinge was found cracked at the forward 

outboard corner of the hinge fitting station 281 at the flap 

link cutout P/N FLA 1055. The flap assembly was replaced. ' 

(4) When the flaps were extended beyond 30 degrees, the aircraft 

would make a turn to the left. Inspection revealedthat the 

outboard flap linkage, P/N 5534780, was broken on the left 

wing flap: The link was replaced. Time since overhaul was 

1,959 flight hours. 

DC-7 AIRCRAFT MAINTENANCE INFORMATZON. The following is a listing of 

significant maintenance difficulties that have been reported by air 

carriers as mechanical reliability reports from 1964 to 1967. This 

information may be useful in identifying additional structural 

inspection areas: 

a. Wings. 

(1) Corrosion was found on the inner strut of the nose landing 

gear where it attaches to the fork. This was repaired by 

replacing the inner strut. Aircraft total time was 24,588 I 

flight hours. 

(2) During.inspection, a two and one-half inch crack was found 

in frame P/N 5361581 at W.S. 50 between longeron 9 and 10 

due to fatigue. Repairs were made in accordance with the 

manufacturer's instructions. AircrafttDtal time was 44,879 

flight hours, 

(3) A one and one-half inch crack was found in the upper wing 

skin during a routine inspection. The crack was located 

approximately two inches inboard of the No. 2 main fuel 

tank filler cap. Repairs were made in accordance with the 

manufacturer's instructions. 

C- c- - 
AC 20-52 

8/24/67 

* Appendix 6 

Page 7 

( 4 1 

(5) 

(6) 

(7) 

(8) 

( 9 1 

During wing flap retraction, bolt P/N 2356375 failed in the 

link assembly P/N 4325008 at W.S. 378. The outboard flap 

shifted outboard riding on top of the right aileron holding 

it in the down position. The link assembly and flap were 

replaced. Aircraft total time was 20,030 flight hours. 

During a routine service inspection, a one-inch crack was 

found in the wing to fuselage attach angle at station 381 

on the right wing. Approved repairs were accomplished. 

Total flight time on the aircraft was 22,621 flight hours. 

The left outboard nacelle circumferential at station 400 was 

found cracked during aircraft overhaul. The crack was 

located at stringer No. 8 inside of the nacelle. A repair 

can be found in the manufacturer's repair manual. 

The attach angle on the outboard side of number one nacelle 

found cracked at the leading edge of the wing. Also, the ' 

inboard top attach angle was cracked at the bolts on both 

sides of the center spar. Approved repairs were accomplished. 

During overhaul, acrack was found on the outboard side of the 

No. 2 nacelle. This crack was located in the nacelle circumferential at station 384 in the "jr' box area. Approved repairs , 

were made in accordance with the manufacturer's repair 

manual. 

During overhaul, the Nos. 2 and 3 main fuel tank doublers 

were found cracked at station 203. The manufacturers have 

a service bulletin covering the repair in this area. 

(10) The fuselage attach angle doublers on top of the left and 

right wings were found cracked during aircraft overhaul. The 

cracks were located at KS. 40. This was repaired by 

replacing the attach angle doublers. 

(11) During a routine heavy service inspection, the wing to 

fuselage attach doubler was found cracked af,t of the top 

forward spar attach fitting. The doubler was replaced. Also, L No. 3 top outboard nacelle attach angle was foundcracked 

in the angle radius. The crack was located approximately 

12 inches forward of the front spar. A repair was made in 

accordance with the manufacturer's structural repair manual. 

The total time on the aircraft was 20,143 flight hours. 

(12) Inspection during a heavy service basic check period revealed 

that the nacelle to wing inboard attach angles in the NOS. 1 

and 2 positions were cracked. The No. 1 attach angle contained a one and three-eighths of an inch chordwise crack 

slightly above th e angle bend radius. The No. 2 attach 
Appendix 6 *, 

Page 8 

AC 20-52 

angle was cracked between the rivets adjacent to the bend 

radius in a chordwise direction approximately one inch forward of the front spar. Also, it had a one and one-half of 

an inch crack in the aft end of the angle in the center of 

the bend radius directly over the rear spar. Both cracks 

were repaired in accordance with approved manufacturer's 

drawings. The total time on the aircraft was 19,345 flight 

hours. 

(13) Inspection revealed-a three-sixteenth of an inch crack in 

the right top wing skin at the outboard aft corner of No. 3 

alternate tank accessory plate cutout. Also the plate landing was cracked. The repair was acComplished by installing 

an outside doubler - 90-7075-56, on the skin crack and the 

accessory door landing was spliced. The total time on the 

aircraft was 15,597 flight hours. 

(14) During a block overhaul, inspection revealed that the left . 

wing skin was cracked from the center spar aft of the access 

cutout at KS. 203. The repair was made in accordance with 

the manufacturer% drawings. A special X-ray inspection of 

station 203 on the right and left wings of the fleet was 

conducted. The total time on the aircraft was 29,850 flight 

hours. 

(15) During a special inspection, the following damage was found on 

the left wing: The upper wing skin was cracked at 16 places 

at station 167 between the front and center spars. The length 

of these cracks ranged from one-fourth of an inch to five 

inches long. Also, the upper wing skin was cracked threefourths of an inch at station 141 between wing stringers Nos. 

. 6and7. In addition, the lower skin was cracked at station 

167. This crack was six inches long and was progressing forwardfrom the rear spar. Repairs were accomplished in accordance with the manufacturer% recommendations. 

(16) Special inspection of the wings disclosed the following damage: 

The right upper wing skin was cracked in seven places between 

the front and center spars at station 167. The length of the 

cracks ranged from one-eighth of an inch to three and threeeighths inches long. The left upper wing skin was cracked in 

16 places between the front and rear spars at station 167. The 

length of the cracks ranged from one-fourth of an inch to five 

and three-eighths inches long. The left upper wing skin was 

cracked at station 133 aft of the center spar. This crack was 

three-fourths of an inch long. Cracks three-fourths of an inch 

long were also found in the upper wing.skin at station 152 just 

aft of the center spar. In addition, seven cracks were found 

just aft of the center spar from station 132 to station 152. 

These cracks were one-eighth to four and seven-eighths inches 

long. The repairs were made in accordance with the manufacturer's recommendations. 
AC 20-52 

8/24/67 

Appendix 6 

Page 9 

b a Stabilizers. 

(1) A nine-inch crack was detected during a routine inspection 

in the lower surface of the left stabilizer at station 107. 

The aft end of the crack was located 12 inches from the 

rear edge of the stabilizer and its direction of progression was fore and aft through the row of rivets attaching 

the skin to the rib. The internal structure of the 

stabilizer was not affected. The repair was made in 

accordance with the structural repair manual. 

c. Hydraulic Systems. 

(1) 

(2) 

(3) 

(4) 

Hydraulic fluid was lost when the flaps were extended during 

descent. Also, when the landing gear was extended, the pressure dropped to 900 p.s.i. Investigation of the aircraft 

after landing disclosed that the manual bypass valve was 

cracked at the fluid port. 

, 

The valve was replaced. 

Hydraulic fluid and pressure were lost during taxiing 

resulting in the use of the airbrakes. Jnspection revealed 

that the inboard flap actuator on the left wing was leaking. 

After takeoff, all hydraulic pressure and fluid were lost. 

Inspection revealed that the manual bypass valve, P/N 

340846601, had failed. The piston, P/N 2243941, failed 

at the lever attach end at the necked-down section in the 

11/32-inch diameter area. The valve was replaced and the 

system operation was normal. 

During taxi after completion of the landing roll, all 

hydraulic pressure and fluid were lost. Inspection revealed 

that the right inboard flap cylinder, P/N 3498899-1, was 

cracked. The flap cylinder was replaced and operation of 

the system was normal. 

d . Landing Gear System. 

(13 The landing gear was lowered for landing and the nose gear 

would not come down. However, after several attempts, it 

did come down and lock.' The aircraft was jacked,and on the 

retraction test, the gear would not move. Upon removal of 

the control valve, P/N 3480940-1, the *@up'* port was found . 

to be blocked. Disassembly of the valve revealed that the 

port was blocked by soft solder. As a result of these 

findings, the hydraulic manifold was replaced and the system 

flushed. 
Appendix 6 

Page 10 

AC 20-52 

8/24/67 

e. Flight Controls. 

(1) 

(2) 

(3) 

. 

.During,routine inspection, the right wing..flap supports at 

station 281 and ths,right and left support‘s at station 372, 

‘P/N 5498283-2 and 549834O"were found to.be corroded beyond 

specified limitations. Corrosion of the supports is considered to have resulted fromthe aircraft being in storage 

for seven months. The total time .on the aircraft was . 

20,143 flight hours. 

During overhaul, zyglo inspection of the elevator torque 

tube revealed that the right end attach fitting,P/N 3536439-3, 

was cracked. The crack was three-eighths of an inch long 

and extended from outboard through the bolthole. The 

defective part was replaced. 

During a maintenance operation, a flap link assembly, 

P/N 549334, was found broken at the outboard end of the 

left flap. The failure occurred in the link-bearing area. 

The total time on the aircraft was 22,249 flight hours. 

f 0 Fuselage. 

(11 The following discrepancies were noted during a routine 0 

inspection: The left side of the fuselage skin was cracked 

in the rivets below the pilot's sliding window at station 

41 The length of the cracks ranged from one-half to 

thiee-quarters of an inch. Eight cracks that ranged from 

a half to one and one-half inches in length were found in 

the skin below the pilot% window at station 22 between 

stringers Nos. 15 and 22. The fuselage skin was also 

cracked onthe left side at stringer No. 15 and F.S. 58. 

The length of these cracks was one and one-half inches in 

length. In addition, cracks one and one-half inches in 

length, were found on the right side of the fuselage at 

stations 21 and 22. Repairs to these cracks were made 

in accordance with the manufacturer's structural repair 

manua 1. The total time on the'aircraft,was 22,621 flight 

hours. 

(2) During a basic check period, the fuselage skin was found to 

have cracked beyond the stop drill hole at the left forward 

emergency exit upper hinge.. Repairs tiere accomplished in 

accordance with the manufacturer% structural repair manual. 

The total time on the aircraft was 20,143 flight hours. 
AC 2Q-52 

8/24/67 

Appendix 6 

Page 11 

(3) A two and one-half-inch crack was found inthe nose gear 

well web on the left side at station 58. The repair was 

accomplished in accordance with the manufacturer's 

structural repair manual. The total time on the aircraft 

Was 19,904 flight hours. 

(4 9 . During the accomplishment of DSB 275, the fuselage formeic 

at F.S. 49.6 was found cracked. The crack was located 

between fuselage stringers Nos. 8 and 9 above the crew 

entry door. Aircraft total time was 28,225 flight hours. 

AC 20-52 CHGl 

7 Jul 72 

Appendix 7 

Page I 

1 . Dc-6/-7 STRUCTURAL INSPECTION ITEMS. 

a. Emergency Exit Door Hinges. 

(1) Location. Fuselage emergency exits (see Figure G-3, Appendix 7). 

(2) Applies to D&6/7 series aircraft. 

(a) Action. All aircraft with emergency exit door hinges with 

less than a one-inch (1") door skin recess radius should 

have the hinges replaced. Applies to all models DC-6 

series prior to serial number 44888 and DC-7 series up to 

serial number 44872 having 32,000 or more hours time in 

service. 

(3) Other Reference Documents. 

(a) DC-6 Service Bulletin 848. 

. 

(b) DC-7 Service Bulletin 393. 

(4) Probable Consequences. Failure of one hinge can cause failure 

of the second hinge resulting in loss of the emergency exit . 

door, 

(5) Recommendations. Periodic inspection, of hinges having l-inch 

door skin recess radius to assure continued structural integrity. 

b l Emergency Exit Door Hinge Cutouts. 

(1) Location. Fuselage Emergency Exits (see Figure G-4, Appendix 7). 

(2) Applies to DC-6/7 series aircraft. 

(3) Other Reference Documents. 

(a) DC-6/*7 Advisory Circular20-52 Appendix 4, Page 10. 

(b) DC-6 Service Bulletin 623. 

(c) DC-7 Service Bulletin 79. 

(4) Probable Consequences. Extension of fuselage cracks initiating 

at hinge radius could result in more extensive structural 

damage. 

(5) Recommendations. 

(a) Periodic inspections until the preventive rework of 

Service Bulletin l 623 or 79 is incorporated. 

(b) Perform subsequent periodic inspections commencing at a 

later date to insure continued structural integrity after 

incorporation of Service Bulletin 623 or 79 preventive 

rework. 

. 
Appendix 7 

Page 2 

AC 20-52 CHG 1 

7 Jul 72 , 

c. Crew and Cargo Door Area. 

(1) Location. Forward fuselage, right hand side (See Figure G-5, 

Appendix 7). 

(2) Applies to DC-6/7 series aircraft. 

(a) Action. Periodic inspections of crew door jamb, adjacent 

skin, longerons, and nose to fuselage attach angles until 

. Service Bulletin 865 has been accomplished. 

(3) Other Reference Documents. 

(a) DC-6/-7 Advisory Circular 20-52 Appendix 4, Pages 3 and 4. 

(b) DC-~ Service Bulletins 616, A636, 636, 731, 775, 788, 815, 

and 865, 

(c) DC-7 Service Bulletins 182, A218, 218, 275, 316, and 417. 

(4) Probable Consequences. Extensive fuselage cracks in this area 

may lead to more serious structural damage. 

. 

(5) Recommendations. 

(a) Periodic inspections should be continued until Service 

Bulletin 865 or 417 is incorporated. 

(b) Periodic inspections should be continued after incofporatlon 

of the Service Bulletin 865 or 417 to assure continued 

structural integrity. c 

d 0 Vertical Stabilizer Front Spar-to-Fuselage Attach Fittings. 

(1) Location. (See Figure G-6, Appendix 7) 

(a) Fuselage Station 1033 (DC-6). 

, (b) Fuselage Station 1073 (DC-7). 

(2) Applies to DC-6 series aircraft. 

(a) Action. Applies to all model DC-6 series aircraft prior 

to fuselage number 221 except 214. 

1 If cracked beyond limits specified, the part should be 

replaced with improved fitting prior to next flight. 

2 If original part is not replaced, inspection should be 

performed every 3500 hours. 

3 DC-7 - None. 
AC 20-52 CHG 1 

7 Jul 72 

(3) Other Reference Documents. 

(a) DC-6/-7 Advisory Circular 20-52, Appendix 4, Page 15, 

(b) DC-6 Service Bulletins 796 and A796. 

(c) DC-7 Service Bulletin 407. 

(4) Probable Consequences. Failure of fitting could result in a 

serious loss of structural integrity of the vertical stabilizer. 

(5) Recommendations. Periodic inspection of original or improved 

fittings to assure continued structural integrity. 

e. Main Entrance Door Area. 

e (1) Location. Aft fuselage, left hand side (see Figure G-7, 

Appendix 7). , 

(2) Applies to DC-6/7 series aircraft. 

(3) Other Reference Documents. 

. 

(a) DC-6/-7 Advisory Circular 20-52, Appendix 4, page 12. 

(b) DC-6 Service Bulletin 583. 

(c) DC-7 Service Bulletins 317 and 400. 

(4) Probable Consequences. Extensive cracking in this area could 

result in more serious structural damage. ' 

(5) Recommendations. Periodic inspections to assure continued 

strut tural integrity. 

f . Fuselage Frames at Wing Upper Spar Cap Attach Area. 

(1) Location. Wing-to-fuselage attach area (see Figure G-8, 

Appendix 7). 

(2) Applies to DC-6/7 series aircraft. 

(3) Other Reference Documents. 

(a) DC-6/-7 Advisory Circular 20-52, Appendix 4, page 8. 

(b) DC-~ Service Bulletins 611, 640, 652, and 789. 

(c) DC-7 Service Bulletins 59 and 346. 

-- 
Appendix 7 AC 20-52 CHG 1 

Page 4 7 Jul 72 

(4) Probable Consequences. Continued cracking can result in a 

significant loss in strength of the wing‘to fuselage attachment. 

(5) Recommendations. Periodic inspections to assure continued 

structural integrity. 

8 

0 Horizontal Stabilizer-to-Tail Stub Front Spar Attach Fittings. 

(1) Location. Outboard end of horizontal stabilizer center section 

(see Figure G-9, Appendix 7). 

(2) Applies to DC-6 series aircraft. 

. 

(a) Action. Applies to following DC-6 aircraft: serial a 

numbers 42854 to 42894 inclusive, 43000 to 43012 inclusive: 

43055, 43056, and 43062. 

1 A 0.25 inch diameter stop hole should be drilled through t'he 

spar cap tang as crack stopper. 

2 Periodic inspection is important when the stop drill hole 

is incorporated. 

2 DC-7 (None). 

(3) Other Reference, Documents. 

(a) DC-6/-7 Advisory Circular 20-52, Appendix 6, Page 5. 

(b) DC-6/-7 Advisory Circular 20-52, Appendix 4, Page 14. 

(c) DC-6 Service Bulletin 831. 

(d) DC-7 Service Bulletin 410. 

(4) Probable Consequences. Continued cracking could significantly 

reduce the strength of the horizontal stabilizer spar joints. 

(5) Recommendations. Periodic inspections to assure continued 

structural integrity. 

h l Wing Lower Front and Lower Center Spar Caps at Wing Station 30. 

(1) Location. Intersection of lower front and center spar caps 

and wing-to-fuselage attach angle (see Figure G-10 Appendix 7). 
AC 20-52 CHG 1 Appendix 7 

7 Jul 72 Page 5 

(2) Applies to DC-6 series aircraft. 

(a) Action. Applies to the following aircraft: DC-6A serial 

numbers 43296, 43297, 43817-43819, 43839-43841, 44063, 

44064, 44069-44073, 44076, 44257. DC-6B serial numbers. 

43257-43259, 43261043276, 43291, 43292, 43298-43300, 435180 

43537, 43539043547, 43549-43555, 43557~43564, 43738-43741, 

43743-43746, 43748~43750, 43820~43822, 43824~43826, 43828~ . 

43834, 43836, 43837, 43842, 43844~43847, 44056-44062, 

44080-44083, 44087-44089, 44102~44113, 44165-44168 and 

44251, 

L If cracks are found, temporary or permanent repair should be 

made. 

2 After permanent repair is incorporated, normal repetitive 

inspection should be made at intervals not to exceed 3,200 

hours time in service. 

, 

2 DC-7 - None. 

(3) Other Reference Documents. 

(a) DC-6/-7 Advisory Circular 20-52, Appendix 5, Page 1. 

(b) DC-6 Service Bulletins A720, 720 and A821. 

(4) Probable Consequences. Cracking of spar cap tangs could lead 

to more serious structural damage. 

(5) Recommendations. Periodic inspections of this area to assure 

continued'structural integrity. 

i . Wing Front, Center, and Rear Spar Caps at Station 60. 

(1) Location. Upper and lower, front, center and rear spar cap 

tangs at station 60 bend area (see Figure G-11, Appendix 7). 

(2) Applies to DC-6/7 series aircraft. 

(a) Action. Applies to all N-6, DC-6A and DC-6B aircraft 

fuselage number 1 up to and including fuselage number 

722 having an excess of 9000 hours in service and to all 

DC-7 and DC-7B aircraft fuselage number 1 up to and . 

including fuselage number 720 having in excess of 8000 

hours time in service. 

1 Temporary or permanent repair should be made if cracks are . 

found. 

2 Periodic inspections should be performed if permanent repair 

is not incorpora ted. 
Appendix 7 AC 20-52 CHG 1 

Page 6 7 Jul 72 

(3) Other Reference Documents. 

(a) ~~-6/-7 Advisory Circular 20-52, Appendix 5, Pages 3 and 6. 

(b) DC-~ Service Bulletins A678, 678, 694, 763, 824, and 857. 

(c) . DC-7 Service Bulletins 167 and 406. 

(4) Probable Consequences. Chordwise cracks in spar caps could 

result in failures in adjacent wing skins and stringers, causing 

a serious loss of structural integrity. 

(5) Recommendations.. Periodic inspections after incorporation of 

respective reworks. 

je Lower Front Spar Cap Splice at Main Landing Gear Drag Attach Brace 

Fittinq. . 

(1) Location. Wing stations 131 and 167 front spar lower cap aft 

tang and splice plates (see Figure G-12, Appendix 7). 

(2) Applies to DC16 series aircraft. 

(a) Action. Applies to all models DC-6, DC-6A and DC-6B aircraft . 

serial number 42854 up to.and including serial number 44429. 

1 A rework should be performed if cracks exist. 

2 Inspection should be made for preloaded flanges. 

2 DC-7 - None. 

(3) Other Reference Documents. 

(a) DC-6/-7 Advisory Circular 20-52, Appendix 5, Page 8. 

(b) DC-6 Service Bulletins 532, 749, 802, and 862. 

(c) DC-7 Service Bulletins 345 and 414. 

(4) Probable Consequences. Cracking in this area could reduce load 

carrying capability front spar splices. 

(5) Recommendations. Periodic inspections to assure continued 

structural integrity. 

k 0 Lower Center Spar Cap Splice at Wing Station 0. 

(1) Location. Wing Station 0 (see Figure G-13, Appendix 7). ' 

(2) Applies to DC-6/7 series aircraft. 
AC 20-52 CHG 1 Appendix 7 

7 Jul 72 Page 7. (and 8) 

(3) Other Reference Documents. 

(a) DC-6/-7 Advisory Circular 20-52, Appendix 5, Page 1. 

(b) DC-6 Service Bulletin 854. 

(4) Probable Consequences. Continued cracking of center spar lower 

cap could result in more extensive structural 

lower panel. 

damage to the wing 

(5) Recommendations. Periodic inspections to assure continued 

structural integrity. 

. 

_ (6) VERTICAL VERTICAL STABILIZER STABILIZER fR()iJT FROiJT SPAR-TO-FUSE~GE SPNI-TO-FUSEl&E 

ATTACH FITTINGS (Page 14) 

(3) EHERGENCY EHERGENCY EXIT DOOR HINGES (Page l ll) ’ 

(4) EftEfXENCY EftERGENCY EXIT DOOR HINGE CUTOUT (Page 12) 

(5)CRfW rfid ,CARGO DOOR ODOR 

AREA (Page 13) 

‘-‘:;I-: 

/\ 

~lgoo33 ~lgoo33 tm .d I ; 1.. 

DOORoR MA (Page 15) 

(8) FUSELAGE'FRAKES AT WING UPPER 

SPAR CAP ATTACH AREA (Page 16) 

L (9) t!ORIZOtlTAL STACILIZER-TO-TAIL 

STUB FRONT SPAR ATTACH FITTINGS 

(Page 17) 

DC-6/-7 FUSELAGE/EWENNAGE STRUCTURAL INSPECTION ITEMS 
. 

LOWER CENTER SPAR CAP 

SPLICE AT WING STA. 0 (Page 21) 

(11) WING FRONT CENTER AND 

REAR SPAR CAPS AT STATION 60 (Page 19) 

(10) WING LONER FRONT AND 

LOUER CENTER SPAR CAPS 

1( (12) ;;$Rs;;;;; AT M L G\ 

AT WING STA. 30 (Page 18) DRAG BRKE ATTACil t IiTIiG- 

(Page 20) 

DC-6/-7 CENTER WIflG STRUCT'iRAL INSPCCTIOM LOCATIONS 
AC 20-52 CHG 1 Appendix 7 

7 Jul 72 Page 11 

FIGURE G-3. EMERGENCY EXIT DOOR HINGES 

B B , 

VIEW A 

EMERGENCY EXIT’ DOOR 

HINGE FITTING 

IHSPECT DOOR SKIN RECESS 1” RADIUS 

VIEW B-B 

. 
Appendix 7 

Page 12 

AC 20-52 CHG 1 

7 Jul 72 

FIGURE G-4. EMERGENCY EXIT HINGE CUTOUTS 

VIEW A EMERGENCY EXIT DOOR 
AC 20-52 CHG 1 Appendix 7 

7 Jul 72 Page 13 

FIGURE G-5. CW AND CARGO DOOR AREA 

@l’YP. CRACK LOCATIONS 

i” TYP. CRACK L 

I ’ 

VIEW B-B 

VIEW A (VIEhI LOOKIHG INBD & AFT) 

IIISPECT HINGE CASE AND HINGE CUTOUT SECTION C-C (ATTACH AMLES) 

INSPECT RADII AND AROUND FASTENER 

HOLES BETlaJEEN LOi’G. 11 IUD 17 
\I 

\I 

N 

R 

N 

0 

i 
AC 20-52 CHG 1 

7 Jul 72 

Appendix 7 

Page 15 

FIGURE G-7. MAIN ENTRANCE DOOR AREA 

INSPECT SKI14 AT RADIUS CUTOUT--, 

(DC-G) STA. 661 (DC-G) S-M. 7i:l-I 

(DC-7) STA. 701 (X-7) SX, 741 

22 . 

RACK LOCATICM 

6 

/\- 

TYPIC nf nL rno cm run Jl?\. 7m IV I -- -- -- 

VIEW A (VIEW LOOKII:G 111bD & AFT) 

IMSPET.T~E CASE MD HIIIGE CUTOUT . 
m 
. 

AC 20-52 CHG 1 

7 Jul 72 

Appendix 7 

Page 17 

FIGURE G-9. HORIZONTAL STABILIZER-TO-TAIL STUB FRONT SPAR ATTACH FITTING 

TYP. C RAC 

REAR SPA; R 

STUB 

ACCESS PANEL 

STA. 48.8 STA.62 

-- -T- --- ir 

STA.77 

FROiJT SPAR - A 

--- 

. 

A A 

HORI ZO?ITAL ST/X ILIZER-TO-TAIL STUI; KX-.i: 

- -- - 

/ 

/- TYP. CRACK LOCATIOM c 

VIEW A-A 

- OUTUD 

TYPICAL FOR UPPER AXI LONER FITTINGS 
W 
c 

Y 
1 
AC 2042 CHG 1 

7 Jul 72 

FIGURE G-13. LOWER CENTER SPAR CAP SPLICE AT STATION 0 

Appendix 7 

Page 21 

CENTERL INE 

AIRPLAilE 

VIEW A-A 

LOWER &iii-iiiR CAP 

I 

I I 

, I 

UP 

1 

I 

AFT 

SECTION B-B 

(TYPICAL) 

* U.;%VERIIYENT PRIIITMG OFFICE: 1979 -627-473/1838