<PAGE>
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
 
                               ----------------
 
                                 SCHEDULE 14D-1
                                
                             (AMENDMENT NO. 2)     
 
                   TENDER OFFER STATEMENT PURSUANT TO SECTION
                14(D)(1) OF THE SECURITIES EXCHANGE ACT OF 1934
 
                              GRUMMAN CORPORATION
- --------------------------------------------------------------------------------
                           (NAME OF SUBJECT COMPANY)
 
                           NORTHROP ACQUISITION, INC.
- --------------------------------------------------------------------------------
                                    (BIDDER)
 
                    Common Stock, $1.00 par value per share
                       (Including the Associated Rights)
- --------------------------------------------------------------------------------
                         (TITLE OF CLASS OF SECURITIES)
 
                                    40018110
- --------------------------------------------------------------------------------
                     (CUSIP NUMBER OF CLASS OF SECURITIES)
 
                            Richard R. Molleur, Esq.
                              Northrop Corporation
                             1840 Century Park East
                             Los Angeles, CA 90067
                                 (310) 553-6262
 
                                    COPY TO:
 
                             Karen E. Bertero, Esq.
                            Gibson, Dunn & Crutcher
                             333 South Grand Avenue
                             Los Angeles, CA 90071
                                 (213) 229-7000
- --------------------------------------------------------------------------------
                 (NAME, ADDRESS AND TELEPHONE NUMBER OF PERSON
     AUTHORIZED TO RECEIVE NOTICES AND COMMUNICATIONS ON BEHALF OF BIDDER)
 
                           CALCULATION OF FILING FEE
- --------------------------------------------------------------------------------

<TABLE>
<CAPTION>
           TRANSACTION VALUATION*                       AMOUNT OF FILING FEE**
<S>                                                     <C>
              $2,104,030,800.00                              $420,806.16
</TABLE>

- --------------------------------------------------------------------------------
 
*  For purposes of calculating fee only. Assumes purchase of 35,067,180 shares
   of Common Stock, $1.00 par value per share, of Grumman Corporation at $60.00
   per share.
 
** 1/50th of 1% of Transaction valuation.
 
[_]CHECK BOX IF ANY PART OF THE FEE IS OFFSET AS PROVIDED BY RULE 0-11(A)(2)
   AND IDENTIFY THE FILING WITH WHICH THE OFFSETTING FEE WAS PREVIOUSLY PAID.
   IDENTIFY THE PREVIOUS FILING BY REGISTRATION STATEMENT NUMBER, OR THE FORM
   OR SCHEDULE AND THE DATE OF ITS FILING.
 
Amount previously paid: Not Applicable              Filing party: Not Applicable
                                                       
 
Form or registration no.: Not Applicable            Date filed: Not Applicable
                                                        
 
                               Page 1 of 4 Pages

<PAGE>
 
   
  This Amendment No. 2 amends and supplements the Tender Offer Statement on
Schedule 14D-1, dated March 14, 1994 (the "Schedule 14D-1"), of Northrop
Acquisition, Inc. (the "Purchaser") and Northrop Corporation ("Northrop"), as
amended, filed in connection with the Purchaser's offer to purchase all of the
outstanding shares of Common Stock, par value $1.00 per share, of Grumman
Corporation, a New York corporation (the "Company"), and the associated
preferred stock purchase rights, as set forth in the Schedule 14D-1.     
 
ITEM 3. PAST CONTACTS, TRANSACTIONS OR NEGOTIATIONS WITH THE SUBJECT COMPANY.
   
  On March 23, 1994, Northrop sent a letter to the Company, a copy of which is
attached hereto as Exhibit (c)(5) and incorporated herein by reference in its
entirety. On March 24, 1994, Northrop received a letter from the Company, a copy
of which is attached hereto as Exhibit (c)(6) and incorporated herein by
reference in its entirety.     

TEM 11. MATERIAL TO BE FILED AS EXHIBITS.
       
   
  (c)(5)   Letter dated March 23, 1994 from Northrop to the Company.     
    
  (c)(6)   Letter dated March 24, 1994 from the Company to Northrop.      
         
                               Page 2 of 4 Pages

<PAGE>
 
                                   SIGNATURE
 
  After due inquiry and to the best of my knowledge and belief, I certify that
the information set forth in this statement is true, complete and correct.
   
Dated: March 24, 1994     
 
                                        NORTHROP CORPORATION
 
                                        /s/ Richard R. Molleur
                                        ----------------------------------------
                                        Name: Richard R. Molleur
                                        Title: Corporate Vice President
 
                                        NORTHROP ACQUISITION, INC.
 
                                        /s/ Richard R. Molleur
                                        ----------------------------------------
                                        Name: Richard R. Molleur
                                        Title: Vice President and Secretary
 
                               Page 3 of 4 Pages

<PAGE>
 
                                 EXHIBIT INDEX
 

<TABLE> 
<CAPTION>

 EXHIBIT                                                                               SEQUENTIALLY
   NO.                         DESCRIPTION                                             NUMBERED PAGE
 -------                       -----------                                             -------------
<C>          <S>                                                                       <C>
       
   
  (c)(5)  Letter dated March 23, 1994 from Northrop to the Company.      
    
  (c)(6)  Letter dated March 24, 1994 from the Company to Northrop.      
</TABLE>


                               Page 4 of 4 Pages





<PAGE>
 
                                             Corporate Vice President and 
                                             Chief Financial Officer      
                                             ----------------------------------
   [NORTHROP LOGO]                           Northrop Corporation              
                                             ---------------------------------- 
                                             1840 Century Park East             
                                             Los Angeles, California 90007-27xx 
                                             Telephone 310-563-5282             
                                 
                                   March 23, 1994               
                                                                          
VIA FACSIMILE
- -------------

Mr. J. R. Anderson
Vice Chairman and Chief Financial Officer 
Grumman Corporation
1111 Stewart Avenue
Bethpage. NY 11714-3580

Dear Bob:

It has now been more than 10 days since we wrote you to advise that our
Board of Directors had authorized the acquisition of Grumman at a price
$5 per share in excess of the amount offered by Martin Marietta and that
we are prepared to enter into a tender offer/merger agreement with
Grumman on substantially identical terms to those in the Grumman-Martin
Marietta agreement.

We appreciate the opportunity we were afforded to do limited "due
diligence" at Grumman last week, and I can advise that what we learned
has confirmed our strong desire to complete the acquisition. We are very
firmly of the view that there is greater value in a combination of Grumman with
Northrop than with Martin Marietta and the results of a free and open bidding
process will confirm that view.

We do not, of course, have knowledge whether Martin Marietta is
considering an increase in its offer price. If
 Martin Marietta determines
to do so, we would object most strenuously to any amendment of the
existing Grumman-Martin Marietta agreement that would have the effect of
erecting still further barriers (in the form of increased "lock-up" fees
or otherwise) to a free and open competitive bidding opportunity for
Northrop.

It would be absolutely contrary to the best interests of Grumman's
stockholders if Grumman were to tilt the playing field against Northrop
once again by entering into further lock-up arrangements or by otherwise
favoring Martin Marietta.

Accordingly, we are requesting assurance from Grumman, in writing, by
close of business Pacific Standard Time on Thursday, March 24, 1994, to
the following effect:


<PAGE>
 
Page 2

(a) That Grumman will not amend or revise the existing merger agreement
between it and Martin Marietta in any respect that would impede or make
more expensive the acquisition of Grumman by Northrop, except for any
increase in the consideration payable to Grumman stockholders.

(b) That Grumman will take no action that would impede a free and open
competitive bidding and the ability of Northrop to submit to the Grumman
Board of Directors and stockholders a competing offer to any further offer
by Martin Marietta for the acquisition of Grumman and will take such
actions as may be necessary and appropriate to afford Northrop the
opportunity to do so.

                               Sincerely,

                               /s/ RICHARD B. WAUGH, JR.

                               Richard B.Waugh, Jr.



<PAGE>
 
[LETTERHEAD OF GRUMMAN CORPORATION]

                                                              J. Robert Anderson
                                                      Vice Chairman of the Board
                                                     and Chief Financial Officer

                                 March 24, 1994

Mr. Richard B. Waugh, Jr.
Corporate Vice President and
 Chief Financial Officer
Northrop Corporation
1840 Century Park East
Los Angeles, CA  90067

Dear Dick,

     Pursuant to the request set forth in your letter to me
dated March 23, 1994, this will advise you that Grumman
Corporation will not take any action except to the extent that
the Board of Directors of Grumman Corporation determines in its
reasonable good faith business judgment that it is in the
interest of the shareholders of Grumman Corporation to take such
action.

     Please be advised that the Board of Directors of Grumman
Corporation pursuant to Section 6.2 of the Merger Agreement
between it and Martin Marietta has today authorized entering
into discussions with Northrop.


                                           Sincerely,
 
                                           /s/ J. R. ANDERSON

                                           J. R. Anderson
JRA:rk

cc:  Martin Marietta Corporation
     6801 Rockledge Drive
     Bethesda, MD  20817
     Attn:  General Counsel