TM 1-70-23AW-2 

TECHNICAL MANUAL 

AIRWORTHINESS LIMITATIONS MANUAL FOR 

SIKORSKY MODEL 

S-70 FOREIGN MILITARY SALES AND COMMERCIAL HELICOPTERS 

OPERATING UNDER FEDERAL 

AVIATION ADMINISTRATION CERTIFICATION 

THIS MANUAL SUPERSEDES TM 1-70-23AW-2 DATED 1 FEBRUARY 1999, WITH CHANGE 

INFORMATION. CHANGE 3- 15 APRIL 2012 HAS BEEN INCORPORATED IN THIS ISSUE 

AND MAKES THIS A COMPLETE MANUAL. 

WARN NG: -MIS DOCUMENT, CR AN EMBODIMENT OF IT IN ANY MEDIA, DISCLOSES INFORMATION WHICH IS PROPRIETARY. IS THE PROPERTY OF 

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AND IS DELIVERED ON THE EXPRESS CONDITION THAT IT IS NOT TO BE USED, DISCLOSED, REPRODUCED, IN WHOLE OR IN PART (INCLUDING RE. 

PRODUCTION AS A DERIVATIVE WORK), OR USED FOR MANUFACTURE FOR ANYONE OTHER THAN SIKORSKY AIRCRAFT CORPORATION AND/OR 

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HEREIN, ALL RIGHTS RESERVED. ANY ACT IN VIOLATION OF APPUCABLE LAW MAY RESULT IN CIVIL AND CRIMINAL PENALTIES. 

EXPORT WARNING: THESE COMMODITIES, TECHNICAL DATA OR SOFTWARE ARE SUBJECT TO THE EXPORT CONTROL OF EITHER THE INTERNATIONAL TRAFFIC IN ARMS REGULATIONS (ITAR) OR THE EXPORT ADMINISTRATION REGULATIONS (EAR) AND CANNOT BE E XPORTED WITHOUT THE 

PRIOR AUTHORIZATION OF EITHER THE DEPARTMENT OF STATE OR THE DEPARTMENT OF COMMERCE. THE TERM "EXPORT' INCLUDES DISCLOSURE AND/OR PROVISION OF ACCESS TO COMMODITIES, TECHNICAL DATA OR SOFPNARE TO OR BY FOREIGN NATIONALS (WHETHER LOCATED 

IN THE UNITED STATES OR ABROAD). THIS REQUIREMENT ALSO APPLIES ro FOREIGN NATIONAL EMPLOYEES OE U.S. COMPANIES AND THEIR 

FOREIGN SUBSIDIARIES. 

SIKORSKY AIRCRAFT CORPORATION - 24 MARCH 1997 

CHANGE 3- 15 APRIL 2012 

SIKORSKY AIRCRAFT CORPORATION 

24 MARCH 1997 
TM 1-70-23AW-2 

TECHNICAL MANUAL 

AIRWORTHINESS LIMITATIONS MANUAL 

FOR 

SIKORSKY MODEL 

S-70 FOREIGN MILITARY SALES AND COMMERCIAL HELICOPTERS 

OPERATING UNDER FEDERAL 

AVIATION ADMINISTRATION CERTIFICATION 

TABLE OF CONTENTS 

Change 3 
a. Determine number of hours on component. 

b. Determine the percentage of life used using the 

following equation: 

No. of hrs on component = % of life used 

Life Limit 

where the life limit is from the aircraft the component 

was removed from. 

c. Multiply the "% of life used" calculated above 

by the "Life Limit" of the part for the new 

model aircraft to determine the equivalent 

number of component hours consumed on the 

new aircraft. 

Two sample calculations are presented as follows: 

EXAMPLE A: 

Life limits provided by Sikorsky Aircraft: 

Life Limit Aircraft 

10000 Hours A 

7000 Hours 

5000 hours were consumed while the component was I 

on aircraft A. (Step 1) 

50% of the component life has been consumed. 

0.5 x 7000 = 3500 Hours (Step 3) 

3500 equivalent hours have been consumed on aircraft B and the life limit of the component on aircraft 

B remains at 7000 hours. 

EXAMPLE B: 

Life Limits Provided By Sikorsky Aircraft: 

Life Limit 

3000 Hours 

5000 Hours 

Aircraft 

5000 Hours= 0.5 = 50% (Step 2) 

10000 Hours 

PARA 1.1 TM 1-70-23AW-2 

1.1.3 Component Life Prorating. 

NOTE 

Many components on the S-70A aircraft 

are common to several other models 

which have different component life 

limits due to different usage and flight 

loads. It is not recommended to transfer 

any components between aircraft models. If the history of an aircraft component is unknown, that component CAN 

NOT be used on an S-70A aircraft. 

However, if an aircraft component is going to be used on a different aircraft 

model with different life limits and a 

known part history, prorating will have 

to be used to determine the equivalent 

life consumed for the new aircraft model 

the part is to be installed on. 

The procedure below can be applied to 

any life-limited component transferred 

between aircraft models with different 

life limits. Part transfer cannot be performed if the component has an "Unlimited" or"On Condition" life limit on one 

aircraft model and a "Limited Life" or 

"On Condition" life limit on another aircraft model, unless a methodology to 

conservatively estimate the component 

life is determined and approved by 

Sikorsky Aircraft. 

To prorate the component lives, the life 

limits for both the aircraft the part was 

removed from and the aircraft the part is 

being installed on will need to be 

known. Contact Sikorsky Aircraft at 

I -800-WINGED-S (1-800-9415-4337) or 

v i a e-mail a t 

sikorskywcstOsikorsky.com , in order to 

determine the appropriate life limits for 

aircraft models. 

The percentage of life is used to determine the component life consumed on 

the new aircraft. The new aircraft's 

component life limit is not changed with 

this procedure. 

Change 3 1-25 
Table 2. Aircraft Prorate Calculation 

1) Aircraft component was removed from: 

2) Recommended retirement time on old aircraft: 

3) Original time since new (Step I): 

4) % of life used (Line 3/Line 2) (Step 2): 

5) S-70A recommended retirement time: 

6) Equivalent time used on S-70A (Line 4 x Line 5) 

(Step 3): 

1200 hours were consumed while the component was 

on aircraft C. (Step I) 

1200 Hours = 0.4 = 40% (Step 2) 

3000 Hours 

40% of the component life has been consumed. 

0.4 x 5000 = 2000 Hours (Step 3) 

2000 equivalent hours have been consumed on aircraft D and the life limit of the component on aircraft 

D remains at 5000 hours. 

The calculated information shall then be documented 

in the REASON FOR REMOVAL section of the 

components log card in the following form: 

A/C removed from: 

Original time since new: 

Calculated % time used: 

Equivalent time used on S-70A: 

TM 1-70-23AW-2 PARA 1.1 

I

The calculated information shall then be documented 

in the REASON FOR REMOVAL section of the 

components log card in the following form: 

Original time since new (Line 3): 

Calculated % time used (Line 4): 

A/C removed from (Line 1): Equivalent time used on S-70A (Line 6): 

1-26 Change 3