DC-9-30 LOSES UPPER AND LOWER FORWARD COWLING ON #2 ENG INFLT.

Narrative

AFTER DSCNT TO BUF WAS STARTED; AT APPROX 19000 FT A LOUD BANG WAS HEARD ALONG WITH A SHUDDER; VIBRATION AND YAW. THERE WAS NO COCKPIT INDICATION OF ANY KIND. ACFT WAS IMMEDIATELY SLOWED TO ABOUT 230 KTS AND I WENT TO THE CABIN TO INSPECT THE ACFT. (AT THE SLOWER SPD; THE VIBRATION AND YAW WERE MINIMAL BUT STILL SLIGHTLY NOTICEABLE.) I SUSPECTED A FLAP; SPOILER OR FAIRING BUT COULD NOT SEE ANY PROB. I THEN LOOKED AT THE ENGS AND NOTICED JAGGED METAL AT THE TOP R ENG JUST BEHIND THE NOSE COWL AND THE TOP PART OF THE COWL MISSING. I RETURNED TO COCKPIT AND PAID PARTICULAR ATTN TO R ENG READING EVERYTHING INDICATED NORMAL EXCEPT THE ENG OIL QUANTITY WHICH SHOWED ZERO. ALL OTHER ENG INDICATIONS WERE NORMAL SO I CONCLUDED IT WAS AN INDICATION PROB ONLY FOR THE OIL QUANTITY. AN EMER WAS DECLARED; THE PAX AND LEAD FLT ATTENDANT BRIEFED AND A LNDG MADE AT BUF. R THRUST REVERSE WAS NOT USED DUE TO THE UNCERTAIN AMOUNT OF DAMAGE TO R ENG. BUF APCH WAS ALSO TOLD OF THE LOCATION OF THE EVENT (DEBRIS FALLING TO GND). THEY SAID THAT PUT US OVER THE LAKE. SHUT DOWN R ENG AFTER CLRING RWY. I INSPECTED DAMAGE AT GATE. TOP OF COWLING WAS MISSING. 60 PERCENT OF BOTTOM COWLING WAS MISSING WITH REMAINING PIECE BENT AFT. OIL WAS DRIPPING OUT OF OIL TANK DUE TO SMALL HOLES PUNCTURED BY FLAPPING DEBRIS FROM REMAINING PIECE OF BOTTOM COWL. PAX DID NOT SEEM UPSET -- JUST GLAD ALL TURNED OUT OKAY. P.S. SPD WAS SLOWED TO 150 KTS AFTER DAMAGE WAS DISCOVERED.